The algorithm of bitcoin is set to be limited so when all bitcoin has been mined, the miners will no longer be able to receive block rewards because there are no more coins to be generated. But why this?
But they can still profit with just transaction fees when all bitcoin has been mined. And with that, bitcoin will be so scarce that the price could literally go very high. So there will be still incentive for miners and unlikely that they will stop mining until the last bitcoin has been mine in 2140 approximately.