The post-Olympiad loss is not the largest loss. Most of the potentially great mathematicians from poorer countries are lost to the world long before the opportunity to participate in an Olympiad. But it is frustrating that even after talent has been identified, it does not always bloom. We are, however, starting to do better. You can see from the graph that upper-middle income countries are as good as turning their talent into results as high-income countries. Agarwal and Gaule also find some evidence that
Source: The Misallocation of International Math Talent – Marginal REVOLUTION