Because with that money you have command of many resources in the Capitalism world. That level of command should always go to public, not private. Public is the lesser evil of the two.
How does the public make decisions about what to do with this much capital? Or are you make the less radical suggestion that it ought to be capped and taxed?
That's very anti-enlightenment values of you. Do you think everything is better handled by committee or just capital allocation?