[amelius]

The problem is the rich using their wealth for more wealth accumulation, e.g. through rent seeking. Even if progressive taxing doesn't get you much money directly, indirectly it will improve wealth through a better wealth distribution.

In other words, it is no problem that the rich have more money; the problem is them using that money against the rest of us. If you don't see how, try entering a game of Monopoly a few rounds after it has started.