We have people sleeping on our streets and kids going hungry in our own communities while governments send billions overseas. It's obscene to claim we can't afford to house or feed our citizens but we can bankroll foreign countries. Charity begins at home—fix your own house before you try to fix everyone else's.
Poverty in the poorest countries is exponentially worse than in wealthy nations, and a dollar goes infinitely further there. A child dying of a preventable disease in a developing country is a greater tragedy than someone in a rich country lacking services. We're wealthy enough to do both, but if we had to choose, the moral math is clear—maximize the good you can actually do.