I need to understand that since the max number of bitcoins that can be generated is capped at 21 million, because of which the blockchain system makes it increasingly difficult to mine the bitcoins, over a period of time, wont the reward proportion be reduced? And if the profit towards mining becomes negative, what will be the incentive for the miners to mine? Moreover, after 2040 (or whenever mining is not financially lucrative), since there will no more bitcoins available, who will act as miners and who will validate the transactions?