Income inequality is not exactly the right metric. Wealth inequality is what matters. But I think that's what you meant because you talked about the bank accoun

Income inequality is not exactly the right metric. Wealth inequality is what matters. But I think that's what you meant because you talked about the bank account. But, anyway - it does matter, obviously. Money are a way for the society to decide what is more important. The more money you have the more decisions in a society you make. If a few people have most of the money - they get to decide for the whole society what is actually happening. TL;DR: high enough wealth inequality turns democracy into oligarchy. Even if it's a nice cozy oligarchy with good social - odds are it probably won't stay that way forever.