1. Outsized political influence (in theory can be mitigated by laws controlling corporate spending, but obviously those laws themselves are subject to manipulation by the rich and powerful)

2. Distortion in who the economy serves. The beauty of capitalism is that it's a problem-detection and problem-solving system. If a narrow set of people have a huge portion of money, the economy becomes unduly optimized toward satisfying their wants and needs.

3. Despite best efforts, we ultimately must share a lot of the same commons. Even being a billionaire in NYC or San Francisco can't really give you a walk to work or your child's school that feels as safe as it does in a more equal society that takes better care of its unwell and poor.