PoS often sacrifices decentralization/censorship-resistance for high performance and cost-efficiency. The only reason ETH chose to become a PoS cryptocurrency is because it needed to scale to millions of users worldwide (especially when it's a platform designed for "decentralized" applications). It wouldn't be possible to achieve high transaction throughput with PoW, because of the time it takes to produce blocks. Bitcoin will never sacrifice its decentralization in favor of a new consensus algorithm which aims to increase scalability of the Blockchain network but would also centralize the same as whales will be able to gain all of the power. In a PoS system, the rich become richer, while the poor, poorer. That's the way it works.

Bitcoin is open source anyways, so there's nothing stopping someone from coming up with a hard fork that would use PoS on top of PoW. Most altcoins are heading towards the PoS direction, so it should only be a matter of time before Bitcoin remains the only PoW cryptocurrency on the market.

right now the network is about 210,000,00thashs of mining rate.
each asic is only Xthash..
that is about 1.3million asics operating 24/7
where there are only 6.25btc roughly on average every 10 minutes or 900 coins a day on average.

if you work out the time for 1 btc. and how much electric them over million asics and their hardware cost it requires to mine.. (at the cheapest most efficient amount on the planet) for the time to mine that 1 bitcoin.. you work out that it costs that (low) amount to mine 1 bitcoin..
because yes math...  math is great like that..
if you have only a small amount of hashpower it takes longer to mine enough shares of rewards to total the same 1bit which works out at the same cost (if the variables dont change)

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that estimate is like the lowest known way to get the cheapest btc (for those lucky to get the coin for that price)

no one wants to sell for a loss
and if there are people with higher electric.. like in hawaii where it would cost them $80k+ to mine.. they would prefer to buy bitcoin at any price below $80k rather then mine at a loss..
(they are stil very very happy with the $20k-$24k amount this month)
so its market economics. if only a couple people can sell and profit at low number, but the average market is at $20k. and some people cant mine for under $80k
there are alot and i mean alot of buyers willing to pay anything at different amounts.. above (low)
and no one willing to sell below the (low) this the low becomes a wall/ a support. and stopping point of where sells dry up, IF it ever went town to that amount

thus this (low) amount which is the current whole planets lowest amount people can get bitcoin for.. thats the 'bottom'

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yes bitcoin cost is actual real world costs.. its not something that can be got for free. there is a cost in one way or another.. thus the bottom is non-zero.  
there is a limit to how low it can go at current variables.. where everyone just gives up trying to sell because sellers run out and too many buyers are eating up them sells before it gets close to the 'bottom'(low)

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bitcoin would literally have to break. where utility/desire dies, and everyone just wants to escape even if everyone makes a loss escaping. for the price to tank right down, breaking the economic low of sane value and market economics,  to near zero,

You cannot sacrifice decentralization if the project has already achieved decentralization because this is how decentralization works! The reason Ethereum was able to switch to another consensus mechanism (though PoS is clearly not a consensus mechanism since you cannot come to consensus by only referring to internal processes that depend on the existence of consensus - circular logic that leads to nothing but an inevitable capture and centralization) is due to the fact that it has never been truly decentralized - developers and founders of Ethereum have had enormous power over the protocol and always could dictate its course and development. The main reason they unilaterally "decided" to shift to PoS is that this way, they can enrich themselves more quickly and efficiently and gain even more power over the project's fate and perhaps over the monetary system itself. Scalability is not their concern, and Vitalik Buterin claimed many times that PoS itself has nothing to do with the speed of transactions and that additional improvements, such as sharding, need to be implemented to make blockchain more scalable. The problem, again, is that sharding makes blockchain even less decentralized because it incentivizes users or stake maintainers to keep only their "part" of the blockchain and trust others with keeping other parts of the blockchain in a correct form. PoS is terrible, PoS with in-built sharding is even worse. Bitcoin doesn't need all that: it has gotten layer 2 solutions such as Lightning Network which, among other things, doesn't make the underlying layer less reliable and less decentralized.

I honestly can't see the difference between those two because if you have influence in a network that is supposed to be decentralized and free of any elite groups able to dictate what needs to be done, you can gaslight less technically competent users and convince them that all changes you propose and make are actually good for them and the protocol as a whole. In my view, it is just synonymous with having control over people's minds. Moreover, you are talking about voting and other democratic terms, but you must have forgotten that in decentralized blockchains, people vote with the software they are running - full nodes. You don't need polls on Twitter or something like that to express your opinion regarding changes in a consensus mechanism: you merely install a piece of software that enforces certain rules with which you agree. The problem is that in Ethereum no one, except for big companies, runs a full node, and therefore, ordinary users don't have real power to influence the fate of a project. Instead, big corporations like Amazon, Infura, Alchemy, Circle, etc decide whether to switch to Proof-of-Stake or not, whether to give users access to certain smart contracts, and so on. Users have neither the right to vote nor the power; they are at the mercy of these big corporations controlling nodes, developers making changes, and governments regulating everything.

That's certainly true, mate. Developers have a high concentration of power within the Ethereum project, yet they claim the Blockchain is completely decentralized. There's a lot of focus on ETH creator Vitalik Buterin, so anything he says or does can either negatively or positively impact the project itself. Not like Bitcoin whose creator and developers are unknown by the general public. In order to achieve true decentralization and censorship-resistance, there must be no personally-identifiable information of the project's founders and/or developers.

One thing for sure is that PoS will only make matters worse as developers and big whales will be able to control the Blockchain to their own will. The little guy will be completely out of the system, making the PoS coin no different than a corporation or any ordinary central bank. It's a pity since this shifts us from Satoshi's original vision of decentralizing everything. People are free to choose their own path, but Bitcoin will always remain a PoW cryptocurrency no matter what. Who knows if BTC becomes the only PoW cryptocurrency in existence while the rest switch to PoS? Just my thoughts

I'll answer the question from a different perspective (by the way I agree with most here that PoW is way superior to PoS, but there's a much better megathread for that).

Let's consider the scenario the Core developers, from whatever inexplicable reasons (a "vision" changing their mind, a chip implanted from governments or another weird conspiracy, haha), decide to implement PoS - very similar to what Ethereum is doing just now. So they prepare the upgrade for block X.

Would everybody upgrade? Well, those which certainly won't, are the miners. First, they probably are unhappy with the change. But second, they have nothing to lose if they simply stay with the old client, as they can't generate blocks (by mining) with the new version from block X on.

If enough miners continue mining to prevent the block time becoming too long and persist so until the next difficulty change, then the original Bitcoin chain will persist.

In this case, basically BTC-PoS, "technically" spoken, would become a hard fork of Bitcoin, very much what BCH is now. The only difference to BCH is that it would be endorsed by Core, but it's still a departure from the original Bitcoin protocol.

Maybe Core reaches a consensus with most major exchanges to just "consider BTC-PoS the 'real' BTC". Maybe many governments ban PoW (it's difficult to ban it outright as you can't ban "hashing", but they can do things like a ban PoW coins from exchanges, like the EU proposed for some time). Thus the BTC-PoS chain has a good chance to become stronger than BTC-PoW.

But there is a group which I estimate pretty big which will continue to ignore the update to PoS: all the Bitcoiners who believe that only PoW provides true decentralization. So BTC-PoW would probaly never cease to exist. If governments ban it, they'll set up exchanges in places where it isn't banned. Or use P2P and atomic swap methods, or simply using it, exchanging it for goods and services.

Even with ETH this is likely to happen - ETHW (EthereumPoW) is preparing its fork (or "refusal to upgrade") and its already traded on some exchanges. Although as some have noted, Ethereum has already a high centralization degree, so PoS will be embraced by more Ethereum folks than Bitcoin folks.

Another thing: If Bitcoin's PoW changes to 100% renewable energy, then there isn't any argument for PoS left at all (at least for Bitcoin). This would be a heavy blow for PoS coins - most will probably disappear. So Bitcoiners should do everything, even if it's impossible to enforce at protocol level, to make 100% renewables happen.

there already are many bitcoin PoS so if governments want one. they can go play with them right now.

to actually cause the real bitcoin to be obliterated where users just use a forked pos coin. would require it to be impossible to solve blocks on bitcoin. this would be the same mechanism of ethereum.
basically, have everyone use an implementation for PoW where every difficulty adjustment increase by 75% EVERYTIME, no matter what..  so that it becomes too difficult to solve blocks intime and never able for asics hashing power to catch up. thus stalling blocks.

i dont think anyone would agree to accept a bitcoin implementation release that allows this where the difficulty of bitcoin PoW is forced to exponentially increase 75% every fortnight. while also releasing a PoS fork to offramp utility too

breaking bitcoins fundamental rule of difficulty (2016 blocks a fortnight, which is the bases of the halving at 210k blocks per 4 year, which is the bases of the 21m cap by 2140~)
is a breach of the protocol. which then is a breach of the immutable rules that made bitcoin a trusted currency in the first place.

once you start messing with the consensus rules/fundamental rules that should never change. it then makes the coin then not a trusted store of value/trusted network of peoples value

PoW miners don't have to agree to anything,
all that has to happen is the developers update the code.
If BTC converted to Proof of Stake , it would finally give people a reason to run a full node with a full history always back to the genesis block,
instead of that pruned PoW node nonsense that will eventually cause the destruction of BTC by losing the blockchain history.

The Miners wanted larger blocksizes, the developers aka blockstream refused them and shoved segwit in instead.
Once a few more Bans take place, it is evolve or die for btc.
Staying a useless waste of energy that btc currently is , won't be allowed in the future.

The debate that btc community is hiding from,
is what will happen to btc,
1. When the energy is no longer available at the current supply.
2. When the Governments just outright ban it for wasting energy.

Evolve or Die, that is btc only options.

This is a misconception. People who have at least some understanding of the technology believe that so far there has not been any proposal that can provide better decentralization that PoW. And we know for sure that PoS provides no security or decentralization.
But we are all open to proposals that can provide a better algorithm.

This is unlikely because of the minefield that the centralized authority has left in the code. In other words if the miners were to decide to remain on the main chain (like ETC aka the original ethereum) they would have to perform a hard fork themselves to defuse those mines!

I disagree. PoS is there to ensure shitcoins that can not attract miners (to provide security for they dying chain) remain alive. Take ethereum for example, when they switch to PoS even if everyone abandoned it they still have the 72 million premined coins and can ensure its survival. But if they continue on PoW, as miners leave the hashrate drops and it becomes susceptible to 51% attacks and their 72 million premine can not help them there.

Their arguments against bitcoin also has nothing to do with energy, they are just using that as an excuse since someone started the FUD a while back and it worked.