Ultra rich in fiat have enormous power because of incentives and power structure set by politicians.
Corruption does not spontaneously generate. You have put the cart before the horse; it is the ultra rich that have created that power with their wealth.
Ultra rich in bitcoin will have great power too. They will set very strong incentives. For example they can desire space travel or building private islands with self-sufficient communities realizing their social utopias. They can have most exotic whims, even perverse ones and they will offer so good price that people will compete almost to death to fulfill those whims.
This is wishing for the "magic spell" that I mentioned, that giving (relatively random) people immense amounts of power will somehow change the landscape of society for the better. It might, but if history is any indication, it probably won't. And in all likelihood, Wall Street will probably reward those with a golden parachute in return for
also having a significant amount of control over bitcoin. In which case it's mostly the same people again.
But in Bitcoin world it would be enormously more difficult to ultimately force people to trade with ultra-rich. The freedom is in the choice to refuse offer 500 Milions USD for your old house, to refuse even 5 Bilions and to refuse to sell it at all. On the other hand you can not refuse to participate in bailouting TBTF bank if the government decides it is right (and compulsory) thing to do.
While this is a valid point in its own right, it is an externality irrelevant to the landscape within bitcoin. It is an argument that applies to any cryptocurrency.