Well, he is worth over 80Bn, so even if he gets only 5% return...
You know what would have been even more amazing? If Microsoft had not landed in its monopolistic position it had. Then all that money that landed at bill gates which is even more, could have been spent earlier on philanthropic means.
Why do you think that money would have necessarily gone to philanthropy?
That is not necessarily true. That money might not have saved lives. You cannot say that for sure.