from web site
Even when numerous miners split these rewards, there is still ample incentive to pursue them. Each time a new block is mined, the successful miner receives a bunch of newly developed bitcoins. In the beginning, it was 50, but then it halved to 25, and now it is 12. 5 (about $119,000 in October 2019).
At that point, all 21 million bitcoins will have been mined, and miners will depend entirely on fees to maintain the network. When crypitol.com was released, it was planned that the total supply of the cryptocurrency would be 21 million tokens. The reality that miners have organized themselves into swimming pools stresses some.
They could also obstruct others' deals. Merely put, this swimming pool of miners would have the power to overwhelm the dispersed nature of the system, confirming fraudulent transactions by virtue of the bulk power it would hold. That might spell the end of Bitcoin, but even a so-called 51% attack would probably not allow the bad stars to reverse old transactions since the evidence of work requirement makes that procedure so labor-intensive.
When you manage the entire currency, with whom can you trade? A 51% attack is a financially suicidal proposition from the miners' point of view. When, a mining pool, reached 51% of the network's computing power in 2014, it voluntarily promised to not exceed 39. 99% of the Bitcoin hash rate in order to maintain confidence in the cryptocurrency's value.