How do you decide how much wealth someone can have? If you say let's do it democratically who's involved in that democratic decision? The people who's wealth

How do you decide how much wealth someone can have? If you say let's do it democratically who's involved in that democratic decision? The people who's wealth is going to be ... eh, uncontrolled? And is it undemocratic if they decide they don't want that? Isn't it possible that we're actually doing what you want - stopping people from having undemocratic control over wealth but we just put the line over how much in a different place then you seemingly want to?