I need some help on Proof of stake

It seems to me although I'm still working through this that proof of stake can be abusively used to turn a decentralized system into a centralized one. In essence are you not just paying to be a trusted node in the system. Obviously the higher the stake the more perceived (trust) in that node because they have more to lose if things go wrong (theft, fraud) with that node. So as the system grows what's to stop the creators of the blockchain from raising the stake to levels that only whales can afford?. In my mind this could place the control of the blockchain in one entities control. Can someone help with this summation? Tell me I'm wrong by telling me I'm wrong. I understand the benefit so no need to go down that path.