As we all know BITCOIN mining will stop once the 21 million mark is reached. According to the information we have 19 millions coins were mined and now circulating. The remaining balance is about 2 millions to be mined. Why it is not possible to mine the remaining BITCOINS before 2140 when the 19 millions mined in just over 10 years?
This is because of the block reward. Every 210,000 blocks mined, the block reward is halved. This means that the amount of bitcoins generated per block decreases over time. As the block reward decreases, the amount of bitcoins that miners can earn for their efforts is reduced, and thus the incentive for miners to continue mining is reduced. As a result, the rate at which new bitcoins are mined will slow down significantly over time until the remaining 2 million bitcoins are mined. This is why it is estimated that it will take until 2140 to mine all 21 million bitcoins.