Whatever power structures are in place, there also needs to be checks and balances between them. Whenever a power structure is based on a positive feedback loop like "having money results in getting more money", it will eventually suck up all the power and resources in its environment. The "trickle down" policies of Reagan when he lifted many of the government regulations on corporations put into play the result of hyper-capitalism we see today. He removed accountability and now the corporations and banks are so intertwined with the policy makers that we live in a corporate dominated society in which it is becoming (or already is) a completely unaccountable, unchecked power structure. The moment corporations "became people" and money was considered "freedom of speech" with no limits set on how much financial contribution can be made to a politician, we ceased to live in a democracy. When socialism ceases to be a democracy it also loses accountability to the people and becomes something oppressive.
It is not as much the nature of the financial system as it is about accountability to the people and checks and balances between existing power structures.