Bitcoin can be at most 21 million by design.
For those who do not know, let's briefly summarize how bitcoin is produced; We have a big ledger (blockchain) that is visible to everyone. When there is a transfer of Bitcoin from person A to person B, it is written in this notebook. The operators managing high-powered computers called "miners" in the network make this transfer real. When they verify the transfers, they receive a Bitcoin reward as an incentive. This reward is currently 6.25 BTC per block.
When Bitcoin first came out, the reward per block was 50 BTC, and by design, this award is halved every 4 years.
Bitcoin will continue to be halved as follows. Although it is not known which month the halving coincides, we know that it occurs every 4 years.
Date Range Award
28.11.2012 - 09.07.2016 25 BTC
09.07.2016 - 11.05.2020 12.5 BTC
11.05.2020 - ??. ??. 2024 6.25 BTC
??. ??. 2024 - ??. ??. 2028 3.125 BTC
??. ??. 2028 - ??. ??. 2032 1.5625 BTC
So this means that by 2032 miners will be receiving approximately 1.5625 BTC for each transaction they verify. So the miners' earnings will be very low. After a while, they will only gain from transaction fees.
Brief Summary
Due to the design of Bitcoin, there can be a maximum of 21 million BTC in circulation. The latest coins will be issued in 2140.
When the supply of bitcoin reaches its maximum level, ie 21 million, there will be no more bitcoins to be mined for miners.
From 2140 onwards, miners will only profit from "transaction fees". There will be no such thing as a block reward.
As we mentioned above, there can be a maximum of 21 million Bitcoins in total. So much. Around the year 2140, after all bitcoins are mined, new bitcoins will no longer circulate.
The Bitcoin blockchain is designed around the principle of controlled supply; This means that only a fixed number of new Bitcoins can be mined each year until a total of 21 million coins are produced.
After all 21 million BTC is mined, the network will largely operate as it is now, but it will be a very significant difference for miners. They will no longer be able to receive block rewards and will only have to settle for transaction fees.
So when will the last bitcoin be mined?
About every ten minutes, Bitcoin miners solve a cryptographic puzzle to find a new block and add it to the blockchain. This block is filled with transactions previously pending in the Bitcoin memory pool (mempool) and are usually queued by the size of the transaction fee they provide to the miners.
In exchange for finding a block, miners receive a steady Bitcoin block reward. When Bitcoin was first released, the reward was set at 50 BTC, but this amount is periodically halved, as we mentioned above. This halving happens roughly every four years and continues, reducing the reward to 25 BTC, 12.5 BTC, 6.25 BTC. So far, three halves have been completed. The latest Bitcoin halving took place on May 11, 2020, and the block reward fell to 6.25 BTC after that date.
Bitcoin miners will be able to continue to earn block rewards until a total of 21 million BTC has been produced, and no more new Bitcoin will enter circulation. Just over 18.5 million BTC have now been produced, which means that 88.3% of the maximum supply was produced in just over a decade. However, due to the gradual decline that occurs every four years as a result of the halving process, the final Bitcoin mining will take place 120 years later.
What will the miners do after all bitcoins have been mined?
So after the last bitcoin is mined in 2140, will the miners be unemployed? No. Miners will still be able to make a profit. They will only be able to profit from transaction fees. The block reward return will be eliminated.
However, there is a situation like this. Block rewards make up the bulk of miners' earnings. Transaction fees, on the other hand, correspond to a smaller number than the other.
We can roughly calculate as follows; Approximately 900 BTC is given to miners per day as a reward This equates to approximately $ 21 million at today's BTC exchange rate (23,770 USD). In other words, the amount earned by miners from block rewards in 1 day is approximately 21 million dollars.
So how much do they earn from transaction fees? It is around 30-50 BTC. If we calculate over 50 BTC, miners earn approximately $ 1.1 million in transaction fees within 1 day.
1-day block reward earnings: $ 21 million
1-day transaction fee earnings: $ 1.1 million
You see the difference, right? In other words, by the year 2140, miners will lose a large part of their earnings. So mining will not be very attractive.
Total Transaction Fees (USD)
Of course, all these above are based on the assumption that there will be no changes in the design of bitcoin. Can the bitcoin developers and the community make a joint decision tomorrow and change the half-time or the amount of block rewards? Can change. Possible. However, there is no such consensus as of now. We also know that bitcoin core developers are too "conservative" to touch the core design of bitcoin. Of course, what will happen in the future is unknown.
So, do transaction fees increase?
In 2017, when everyone was flocking to bitcoin, transaction fees increased significantly. At the peak in December 2017, when Bitcoin was worth $ 14,000, the total daily transaction fee had increased to 1,495 BTC. As a result, the miners earned a total of $ 21 million in transaction fees that day. This figure is the same as the miners are currently earning from the block reward. This indicates that something similar may happen in the future. As a matter of fact, in October 2020, as the Bitcoin price rose, transaction fees increased nine times in two weeks, peaking at around $ 14.
To summarize, let's go back to our original question. What will happen after all Bitcoins are mined? There will be no serious difference. The Bitcoin network will continue to function as it is now. The only difference is that miners will no longer receive block rewards, only transaction fees.
By the time the last block is mined there is going to be enough users to pay for the network security, and they will be paying little fees but as well, but many little payments make a bigger payment, and by that time is Bitcoin BCH is allow to grow every human will only use BCH as the real Bitcoin and as the local currency as well. Now if 1MB blocks is the future that will mean you will have to pay 1 BTC for each fees. So in the long run Bitcoin Cash is the real Bitcoin and as today fees were $18 people will noticed that and they will move to the real bitcoin which is BCH. The censorship worked for some time in favor of BTC but now people little by little they are finding out that there is a better Bitcoin that is much cheaper in fiat price and to use as well. And Bitcoin BCH is not only money now is becoming programmable money as well, Bitcoin BCH is the real Bitcoin and is peer to peer currency first and store of value as result of the first function.