For bitcoin network to become insecure the miners have to go away not the investors who buy bitcoin. Such a scenario would require the following three conditions:
1. An alternative cryptocurrency with the same exact mining algorithm as bitcoin (ie. double SHA256 of an 80 byte header)
2. Offering something innovative so that people bother adopting it initially so that it can gain some momentum, a higher price and the incentive for miners to switch over
3. Miners migrating to this altcoin quickly before it is 51% attacked to death itself

These 3 conditions mean it is impossible to have what you call "competitor".
Take bcash for example. It is a shitcoin that has the same mining algorithm as Bitcoin (among other things that are the copied). Since it has nothing innovative, it never got adopted and remained a very cheap shitcoin. That means that shitcoin is susceptible to 51% attack (and it did actually get attacked that way). Something that makes it an even bigger shitcoin.

So we go back to what I said earlier: lack of innovation is the reason for lack of adoption.

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Keep in mind that altcoins don't have to use the same algorithm to be susceptible to this attack. If they choose another mining algorithm, then no matter how high their price goes, they can not attract bitcoin miners because bitcoin ASIC can not be used to mine something else.
The best example here is ethereum which uses another algorithm (uses Keccak/SHA3 instead of SHA2). No matter how much they pumped it in 2017, it could not attract bitcoin miners to threaten bitcoin security.

Again we go back to what I said, lack of innovation is the reson for lack of adoption. Ethereum had some interesting ideas but they were implemented horribly which is why ETH back in 2017 was worth 0.15BTC and it is something like 0.05BTC...

Bitcoin is not a closed system when it comes to economics because there are lots of factor affecting it.  The increase in price of Bitcoin is not as simple as people buying because of profit and price increase because people are buying it.  Remember in this process people also need to sell in order to bag in profit.

Outside from selling, there is also emotional and logical factor included.  There is also the need for adoption, marketing and hype which is outside factor that affect Bitcoin performance in the market.  There is also this manipulation that greatly affect the fluctuation of the Bitcoin economy. 



Each cryptocurrency have their own community and market performance, emerging cryptocurrency can copy the template of Bitcoin but it cannot duplicate exactly the effect of Bitcoin because of the said different market audience. 

People are free to invest their money to any POW that emerge in the market since it is a free market and no one is controlling people on where to invest their money.  Whether we acknowledge it or not, there is always a competition between cryptocurrency since this competition is created the moment a certain new cryptocurrency is created, it is that these later cryptocurrency is unable to best Bitcoin.



It is not the buy and sell of  Bitcoin that made it secure but the hashes produced by mining Bitcoin.  So it would make sense if you stated that if the mining farm that were mining Bitcoin shifted their hashes to other cryptocurrency, it will make the Bitcoin network less secure.


Again it is not the bitcoin market of selling and buying that make the Bitcoin network secure, Bitcoin can be secured even it price collapse as long as the miners remains, after all it is the number of hashes mining to solve the block that has the direct affect tot he security of Bitcoin network.

Thanks for explaining your logic. I don't agree with it. I believe you are basing your claim on the fact that an increasing price allows more mining and thus more security. However, the converse is not true -- increased mining does not cause the price to rise.

The security of the Bitcoin block chain (against a 51% attack) depends on the cost of mining. If users are concerned about its security, then they will increase mining in order to raise the security, even perhaps to the extent of mining at a loss. However, as I mentioned above, the price of a Bitcoin does not depend on the cost of mining.

In economic terms, a less secure network would result in lower demand, which would tend to lower prices.

Ok, i'll correct then.

1. Bitcoin code is open source and have been copied several times and duplicates and variations have been made, sometimes by only changing the name, and i have lost count on the number of forks that derived from it.
2. Your circular argument doesn't really make sense. You are just basically describing popularity.
3. Buying bitcoin forks or altcoins doesn't affect bitcoin network security in any way.
4. Yeah, everyone wants bitcoin network to be secure, bit like i already said. Buying "competition" doesn't affect it.
5. I don't grasp what you are trying to say with point c. Network being less secure wouldn't rise the price, in fact it would have an opposite effect. People are buying it because it's secure. Which is one of the reasons there will be plenty of miners to keep it secure. And as long as that stays decentralized enough, it will stay secure.

And also some people buy bitcoin to store they hold it and wait for a long period of time especially the bullish market. Sometimes they wait for a long period of time like 3 to 4 years until Bitcoin stop pumping again it’s all depends on the time they bought and the time the market start rising repeatedly bitcoin is not something that is not useful Bitcoin is always useful to whatever you are doing with it I believe so much on Bitcoin because you may just buy and when the price pump you make more so Bitcoin is good for us to understand.