Believe it or not, there is a world outside the United States. And believe it or not, there are people (human beings just like us in fact) that live outside the US. Our wealth as a country has enabled us to cure things that dramatically plague other nations. The Gates’ see the turmoil the rest of the world faces and want to do something about it. And still there are haters.
The worst life in America is better than the median life in poorer parts of Africa and Asia. Expanding your mind past what is good for yourself is how you make the world a better place.