Grantis, the point that I did not include is if your income is from investments and dividends, like is the case with the super wealthy, that is CAPITAL GAINS. They don't "go to a job" and make 20 million, well some CEO's do, but there aren't that many of them.
The real wealth is generated from "capital gains" and not earned income.
Currently, capital gains tax is 15% or 20%. Bush set it at 15%, not sure if Obama has changed it yet.
so, if you are a super wealthy person, you probably pay yourself a dollar a year, pay no tax on that, and suck up all the revenue of owning stuff, on which you pay (under Bush) a whopping 15% of it to Uncle Sam, even if you make a billion a year - still 15%.
That is, assuming you collect it in a tax free state, of which there are 4, I believe. You just need a house in one of them (easy to do, with a billion extra dollars), and then you "say" that it is your primary residence.
Voila, no state tax.