I think the Gates Foundation does good work, but the cynical "so what?" is that creating a structure like this to "give away most of his $124bn (£107bn) fortune during his lifetime" (RE the linked article about Bezos) is a ruse to maintain control over the money without paying taxes - while also producing some good PR.

If they truly wanted to just give it away, Chuck Feeney offer a straight forward model for doing so. You just do it. If "giving it away" merely means putting it into a foundation you control, many people would feel that little has, in fact, been given away.