Yup. As one of my economics professors likes to say (paraphrasing): There is no 'natural' equilibrium. The economy develops based on the set of laws already

Yup. As one of my economics professors likes to say (paraphrasing): There is no 'natural' equilibrium. The economy develops based on the set of laws already in place. People earn money based on the 'system' already in place. So the idea of 'fairness' is already an artificial construct. It's far easier to make a billion in a society like the US, than say, Vietnam, or Argentina, or Romania. So in a very real way, US billionaires do 'owe' something to the system that allowed them to attain that wealth in the first place (and that 'something' is pretty much 'everything'). If wealth could be attained completely independently of the 'system', then the distribution of billionaires would be completely different than it is right now.