Bitcoin has a maximum supply of 21 million units. This is part of what makes it valuable; it is limited in supply with a high demand.
New Bitcoin is mined when a miner confirms a transaction. For example, Person A sends 1 BTC to Person B, a miner confirms if this transaction is valid, that is, confirms if Person A has up to 1 BTC in their wallet. If they do and they can pay the transaction fee, the miner can then confirm it and the transaction goes through.
That miner can then add that transaction to the public record (the blockchain). That miner gets both the transaction fee and a block reward. Block reward now is 6.25 BTC.
So a miner gets 6.25 BTC plus transaction fees for confirming a transaction and updating the blockchain.
Currently, Bitcoin circulating suppy is over 18 million and it takes 10 minutes to mine a block, with this two factors and other factors, it is projected that the last BTC will be mined by 2040.
This means by that time, the only incentive miners will have is transaction fees which varies based on the size of the transaction.
Bitcoin will continue to circulate and miners, hopefully, will continue to secure the blockchain. Because without them, transactions will not get confirmed and the system will be dead.
Now, there is another solution- increase the maximum from 21 million.
This is very possible but it would take time to do.
Here is why:
The administration of Bitcoin is decentralized. There is no central authority or body. For decisions to pass, majority of the stakeholders- developers and the community — must agreed.
Why would this take time?
Bitcoin Taproot upgrade went live yesterday. This upgrade will improve privacy in Bitcoin.
The last upgrade for Bitcoin was in 2017 — SegWit. That’s almost 5 years since the last upgrade.
Also, the Taproot upgrade was proposed in 2018, it just took effect yesterday.
The process is really slow. This is one drawback of a decentralized organisation.
How long do you think it will take for an upgrade as big as increasing the maximum limit?
