I can agree with Fred that the bottom should have the basics covered, and that's the most important point here. That is, we want an economic system that allocates more resources to those at the bottom than we currently have.
Where do these resources come from? I think that the presence of billionaires is simply the other side of the mathematical equation here. Assume with me that wealth follows a power law distribution. Presumably we have the ability to adjust the shape of that distribution (as AOC advocates in some way). The outcome of shifting the power law from, for example, alpha=1.5 to alpha=3.5 is a dramatic evening out of the distribution. The curve is flatter and the top earners will have less relative to the average. So you would have fewer billionaires.
OK- instead of flattening out the overall curve, maybe you put a floor instead, as Fred argues for. What part of the distribution would you have to take from to add the extra tail weight? Most of the weight in the distribution is at the head, where the billionaires are... so I would assume it would come from there. Hence, no/fewer billionaires, no?
I think Fred's and others' broader point is that we should continue having incentives for success. I agree. Maybe a little less incentive, though.
I'm glad we have the opportunity to start discussing this topic on a national stage.
EDIT: grammar