This might be exact same question or just the other side of the coin - but I'm primarily interested in a detailed examination of highest opportunity, least saturated altruistic careers inside the nonprofit world. One article I read (I think it was MacAskill's) about the subject labeled the nonprofit world "people rich, money poor" - where is this most not the case?

I realize the truly brilliant, Steve Jobs equivalents can have outsized impacts in a lot of roles, but where might be the highest potential for slightly more ordinary but still very talented folks? How about even more general areas where it really is the case that the nonprofit world is just people poor, if they exist?