Why not fund Americans' educations instead?

Good question! I would love to. I started this when I had very little money as a college student. I could have donated 100% of my money and not made a dent in an American education. With Tanzania I was able to fund a student with so little money, so the leverage was huge.

Eventually I would love to do more work in the US. I'm a postdoc now so I'm still not in a personal position to make a meaningful contribution to an American education, but one day I plan to get there.

Why not fund Congolese educations against? Why not fund Indians' educations instead? Why not fund Cubans' educations instead?

Does it matter? Are these not all people deserving of education?

Because I believe in putting your own nation first before others. It does matter whether you are helping your own people or other people. I will always chose for an American to get a better education over someone from another country if I had a choice.

Where does that come from? Why are people who happen to hold the same passport as you more deserving of your care/attention/resources?

It is not for him to pride himself who loveth his own country, but rather for him who loveth the whole world. The earth is but one country, and mankind its citizens.