Well, the tax rate for people making (say) more than 2 million / year could just be 50%, and then increase by 10% for every 0 added.

$20 million -> 60%

$200 million -> 70%

$2 billion -> 80%

I think that would bring things under control without resorting to extrajudicial means. But apparently, that's completely impossible to achieve in the US, so here we are...