People like this either have tax lawyers to handled the problem, or they have so much money they won't miss a few million here and there.
Many of them have guilt feelings about their success. But instead of giving money to charity out of their own pockets, they prefer to take it out of the pockets of other taxpayers, whom they probably think of as evil conservatives who deserve to get whacked.
Liberalism is mostly about self-delusion and self-congratulation.
I think the phenomenon of the rich liberal can be explained only by the psychological satisfaction it provides. In economic terms, cash ain't the only source of utility.