Who are the rest of us to argue?
Gates, Buffet, and any others are completely free to give their entire fortunes to charity, or for that matter, donate it all to the Federal government. If I ever become wealthy, I'd like to have the choice.
Leaving aside the obvious fact that their money belongs to them, and is not the property of "society" to dispose of--an idea that liberals find inconceivable--I have never seen any evidence that funneling their wealth through Ted Kennedy's fat fingers is any better for society than whatever their children will do with it.
BTW, your simple-minded stereotypical view of greedy conservatives is something I'd expect from others here, not you.