When the first block was mined, the reward was 50 BTC. Miners were mining basically for free, as bitcoin was basically worthless.

Then there was the first halving, the block reward was 25 BTC. Miners were making making.

Then the second halving came, the reward as 12.5 BTC. Miners were mining a lot and making tons of money. Bitcoin price continue increasing.

Then block reward became 6.25 btc. Miners are still mining, hashrate and bitcoin price reached new ATH. And the reward is nearly 10% of the original block reward.

It is probable that in a few decades onchain transactions will be more expensive and most transaction will occur in second layers solutions (like LN). Miners will always be mining, as difficult will change dynamically according to the hashrate. But i believe hashrate will continue increasing for a long time...

The problem is, the less hashpower in the network, the cheaper it is to attack Bitcoin. And you don't need to look at 2140, even just in a few decades the block reward will already be small. It's really impossible to predict if transaction fees will be enough to retain reasonable amount of hashpower, and it's unknown how much hashpower is actually needed to keep the network reasonably secure. There's no point to worry about it, because it's way too distant and unpredictable, and when the time comes, we'll have some solution.

I always like to share this post from Hal Finney when we discuss second layer solutions:


As we know, Hal Finney was the receiver of the first bitcoin transaction.
He is suggesting that only big transactions would occur on chain in the future, and people will use other ways to transact (probably second layer solutions).

I agree that this is a possible distant future. We dont need to put every single transaction in the blockchain.

It's hard to say what will satisfy people 120 years from now. The good news is that the subsidy drops by half every four years and it will probably drop below the transaction fees in a decade or two, so we don't actually have wait 120 years to understand what might happen.

A few people have come up with potential scenarios that may indicate a problem, but the future is still unclear. If you can think of a good (and supported) reason for why transaction fees won't be sufficient, then let us know.

That's a very famous topic that's been discussed quite frequently.

If you need more responses to that question, read these old threads:

• 2012: What happens when all bitcoins are mined?
• 2013: after all BTC has been mined, what then?
• 2019: How will Bitcoin survive after all 21M coins have been mined?

After 120 years could you imagine that what will the prices of bitcoin? Or even it would exist or not? We are taking about a century later so what can be said exactly to that i don't know.Even if it exists the miners will be willing to secure the network out of transaction fees only as there would be more transactions and even some sats would give them enough profits at that time so you see there are always rewards associated with it.But assumptions are there and we can't predict the future.

If bitcoin exist by that time then miners are also expected to be here and you know why? The answer is simple the price of Bitcoin will be hitting the Mars by that time so when we calculate the rewards based on fiat value it is going to be higher than niw even just with the transaction fee alone.

Your thoughts are not weird. As a matter of fact, you are the nth person to have asked this exact same question. What is actually weird is you raising this question at this point, after years and years of discussions on it and probably hundreds, if not thousands, of articles written on it.

Anyway, 2140 is more than a century from now. It is not for us to know the state of Bitcoin or mining at that time. Only time can tell. What is certain is that huge mining companies will definitely desist from operating if ROI is negative for years and years. But since the difficulty will also decrease as a consequence, I don't think mining will ever stop, provided Bitcoin hasn't grown worthless. So the worst thing that could probably happen is that mining will take several steps back, away from being a huge industry. It might go back to the day when it is being done by individuals in their homes.