It'll make the world a better place. Normally that would be a bad argument, but for someone who has pledged 99% of his wealth to charity it might actually be on point.
That maybe true, and Gates seems to be doing some good stuff. But these mega-capitalists are generally destroying the world with their right hands and trying to clean it up with the left.
Better than not trying to clean it up I suppose. Besides, I don't believe they are destroying the world. Changing it, yes.