> if he's really giving 99% of his wealth to charity
By "charity" he means himself, his own charity foundation. He's basically putting the money in another pocket and calling it charity. It's a tax avoidance scam. Cheaper to give away 10% a year in the guise of charity than actually pay the taxes you'd owe.
if he's really giving 99% of his wealth to charity, and on top of that puts effort into where the money goes and that it's put to good use, why do you care that he's doing that for legacy?