Well, he has shirtloads of money. How much of it is he using on worthwhile things?
Last time I saw the figure, he had 29b in his trust (
The Bill & Melinda Gates Foundation). This is the single largest fund of this kind (by FAR) in the world. The interesting thing about this fund, is that it is private, and is administered by a few of his closest people (family/friends).
These are some very smart cookies (hmmm, coookies), so rather than throwing money at things to win votes or to mollycoddle media, to win the flavour of the day, or even to look good in front of friends, they investigate and spend money on research and drug development that will make a difference to the greatest number of world inhabitants, not the loudest.
Malaria for instance, doesn't occur a lot in the US or western countries, so the drug companies don't care about it too much. Go to Asia/Africa and you find major major problems from it, and yet there is not even a fully effective vaccine available. The Gates Foundation & GSK have been trialling new drugs in this area. (also, last year, the poms discovered an antibody which protects against the disease. Now the europeans are spending £17m on the problem as well - not quite 5b, but better than most others.)