because they are human societies?

the only reason the US is richer than nigeria is history. we all began on the same blank slate, it just happened that our society advanced faster than theirs. nigeria and other african countries have been making great progress, and while they still have a long way to go, it's eventually going to happen. meanwhile, our most humane option is to help them survive and develop instead of letting their people starve while we live a luxurious american life