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 the low-income penalty is diminishing over time. As incomes increase around the world it’s as if the entire world’s processing power is coming online for the first time in human history. That, at least, is one reason for optimism.
Source: The Misallocation of International Math Talent – Marginal REVOLUTION