Bitcoin just like Gold must be “mined”. Gold is mined out of the ground and Bitcoin by computational means. They both have a limited supply which lends to the value of each. Bitcoin’s source code requires that it’s supply is limited and finite just as Gold. In fact, the amount of Bitcoin that will ever be produced is set at 21 million Bitcoin and these are released to the supply at the rate of one Block every 10 minutes. In addition to that, the amount of Bitcoin released in those “Blocks” are reduced by Half about every 4 years.
Once the 21 million supply is produced and released Bitcoin the worlds supply will be tapped out, and currently there have been 18.5 Million bitcoins mined. This leaves under 3 million left to be mined and put into circulation. What will happen when ALL Bitcoin are mined is the subject of much debate.
Important to remember: Even though the max number of Bitcoin is reached, because of lost keys, erroneous transactions and people passing away without leaving their private keys instructions to their heirs, the actual amount of available Bitcoin may be millions less!
Understand that Miners not only produce the Bitcoin for circulation into the ecosystem, but also serve to support and maintain Bitcoin’s decentralization Blockchain without a centralized entity controlling it.
Reaching the maximum number of Bitcoin in circulation could threaten the very existence of Bitcoin’s Blockchain if miners abandoned their work; this could mean a central force take over or a total collapse of the network.
Most likely though, Miners will continue to actively compete for the FEES that are paid for each transaction. These fees for a Block are in the hundreds of dollars at this time but could very well raise to thousands per Block in the future as the number of transactions increase.
chart from Investopia shows how Bitcoin has formed peaks within a year and a half of each halvings.
OTHER CONSIDERATIONS ACCORDING TO INVESTOPIA:
“…it’s worth noting that it will be well over 100 more years before the bitcoin network mines its very last token. In actuality, as the year 2140 approaches miners will spend years receiving rewards that are actually just tiny portions of the final bitcoin to be mined. The dramatic decrease in reward size may mean that the mining process will shift entirely well before the 2140 deadline.”
“It’s also important to keep in mind that the bitcoin network itself is likely to change significantly between now and then. Considering how much has happened to bitcoin in just a decade, hard forks, new protocols, new methods of recording and processing transactions, and any number of other factors may impact the mining process. Even more generally, at some point before 2140 bitcoin may very well fall entirely out of favor, essentially rendering moot the entire thought experiment about what happens after the last token is mined.”
Given the information here, we can conclude that Mining Bitcoin will remain profitable even when all Bitcoins are mined. This is due to earning the transaction fees associated with each transaction.