Nothing really but I guess the main thing is to make sure your family is left with enough money. I mean, 10 mil is perfect amount but 250 mil is even better. Now when you're in the double digit billions then there's no point... Which is why Bill Gates is the man for giving most of his money up for research and such.
a lot of that has to do with him and buffet being really good people- you see a lot of rich people passing it on to their kids or spending all they can (cough trump cough) too
