In absolute terms maybe (though there are some glaring exceptions -- Amazon famous literally pays $0 in taxes), but not relative to how much they make.
> To tax people's wealth on top of the standard tax is plain evil,
I don't see any reason why taxing net worth is at all less sensible than income. If anything I think it makes more sense; why should someone who's had a lucky break but is still not rich have to pay taxes like they are?
> will end up driving all the wealthiest people out of the country...
I don't take seriously the idea that any of them are going to give up living in the US over a couple percent of their income (which is what the wealth taxes folks have been talking about would take, at most).