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.