Though I agree that there may be more objectively worthwhile causes, you can make that argument about almost any charitable contribution. Sure, healthcare's important, but there are children starving in Africa. Sure, children in African are important, but we've got at least as serious problems within our given nations. Sure, spina bifida is a serious problem for people who have it, but you're going to probably be benefitting more people by donating to a homeless shelter. Sure, bums are down on their luck, but there's got to be someone out there who's closer to dying. And so on, ad nauseum. To some extent, I think you've got to pick a cause you feel is important and then not worry too much about it. People all over the world are in need of financial support, and any given contribution will improve someone's life in some way.