Free Exchange tries to explain why some of the largest countries fare so poorly in international sporting events:
People...need a certain level of wealth before they are able to take the kinds of risks necessary for what must be one of the highest-risk, highest-return kinds of careers. Take music: it is very easy to ask, why don't more (pick your developing country) people make a career in music or art? Well, because it's risky; risk appetite is low at very low levels of income. It also takes a lot of resources to train a world-class athlete in any sport.