You are effectively wanting to dictate exactly what someone should be allowed to earn, based on arbitrary figures
set by yourself, this has been the folly of leftists world wide, who simply fail to envisage the outcome of such actions.
Billionaires are not suddenly awash with cash by accident, they prosper by taking risks, growing their companies, working
very hard and employing ever more people as the business grows. Whilst this is happening, they are also, by dint of this growth,
paying ever increasing tax into the States coffers.
So, this billionaire, after building his company over a few years, suddenly gets told that, as his wealth has hit $10 billion, that's
more than enough for anybody, pay tax on it now, and have a healthy $8bill in the bank, any future earnings are, from now,
going to be taxed at a far higher rate, as obviously, he doesn't need any more. From that moment, he starts to contract the business
to keep his earnings at the previous level, staff are shed, and the business stops growing, why work simply to pay the majority of
your profit/income in tax?
Result, lower tax take, unemployment, etc; etc;
If tax rates increase beyond a certain median, reduced tax take ensues, I'm afraid you're still living in an economic
fairyland that believes it won't, simply because it sounds, superficially, fair.