Every self-respecting crypto enthusiast has heard about the 51% Attack, in which an error can occur in the Bitcoin code and I think you understand how this will end.
51% attack is NOT some error in Bitcoin code and I don't know how you got that idea in the first place 
Taking over mining hashrate for Bitcoin is almost impossible task, some people tried to take over with various forks but they failed, this is most secured computer network in the whole world, and anyone willing to throw away many can try that again and se how it goes.