One pool cannot "just steal the money" and you know this. It takes six months with a constant 10 minute reminder that your pool is trying to steal the funds. 

Hashers have a ridiculous amount of time to switch, it is very easy to switch, and they are incentivized to switch because the pool is wasting their work.

If a single mining pool has over 51% hashrate, then Bitcoin is in trouble anyway. BIP300 recognizes this and keeps the miners on a very short leash.