You’re vastly overestimating the quantity of high talent internationally. Take a look at the proportion of Colombia’s students that can answer these math problems:
https://www.oecd.org/pisa/test-2012/form/
For example, 25% of Americans could solve problem 4, and 39% of Canadians, but only 2% of Colombians. (But 8% of Chileans, 15% of Serbians, 21% of Croatians.) Problem 5 is USA 9% to Colombia ~0% (Chile 2%). Problem 6, Taiwan is at 18%, USA 2%.
Colombia’s IMO team, drawn from its 50 million people, also gets trounced by Mongolia, population 6 million. And Mongolia isn’t just poor and polluted, half of that 6 million are horses. Only 3.3 million Mongolians are human.
Taking the 25% vs. 2% comparison, we could say Colombia’s quality-weighted population is effectively 50 million divided by 12.5, so it’s effectively a 4 million person country, measured in Americans.