I am one democrat-sided person who doesn't see corporations and financial institutions as intrinsically evil. Bernie is not my go-to guy on corporate behaviour.
But this doesn't mean that corporations never behave badly or that government has no role in regulation. Without governments regulating property by giving it its existence in law, there wouldn't be any businesses in the first place. Regulation is the essence of property value. It provides key elements of its scarcity by giving legal support to a property owner's deeds. Deeds which remove another person's rights to share the use of a piece of property.
Ruleless capitalism is a unicorn. Property's value is dependent on the heap of rules which surround property rights. Too many rules also make a system which is inefficient. Red tape is a nightmare for everyone. At the same time, the tragedy of the commons is that sharing doesn't work either.
So basically, no single principle works. You are trying to manage a complex series of rights and obligations so that you end up with something which functions as well as possible. But hacking away at property rights to produce libertarianism or communism is doomed to failure.