This is the reason there is a incentive in place, miners get the coinbase reward for every completed block and thus encourages them to not attempt to cheat the system as it is far more rewarding to simply mine.
Also, an attempt to cheat the system through.a 51% attack would be quickly discovered and the shady chain would be dropped, so someone who invested millions of USD into buying mining hardware to own over half of the hashrate would be quickly discovered should or when they attempt an attack on the network.
The consensus to drop a shady chain is an example of the decentralization of Bitcoin.
What if they do a 51% attack by having multiple wallets? It would be harder to tell its coming from the same person.
If the counterargument is that the attacker is better off playing by the rules rather than risk bitcoin value dropping to 0 (and therefore losing all his/her resources), well that also applies to proof of stake networks. The person who has 60% eth would rather not cheat the system, else the value of their stake goes to 0.