We need both kinds of people, wealthy benefactors and those who are "on the ground" or so to speak and are wealthy in experience to help. Those who have a lot of resources may not know how best to help, but if they work with say a mother Teresa, then the value of their resources can go even further. Bill Gates does set a great example though, I think, where he is learning as much as he can about these topics so that he himself is educated in them, which is extra effort in being helpful.
But larger system wide changes are needed the most, I think, so that the many aren't dependent on the whims of the rich few... Universal basic income would probably help a lot of people not need extra help, but where would those resources come from?
Yes, I agree. It's nice for rich people to make a big impact, but unfortunate that we have to depend on that as a society.