I think Poland is in very similar spot, often punching above its weight in software and math. My own amateur explanation is that Polish language is pretty complex and very particular about correct words and word forms. So Polish kids get a good training in keeping track of details of notations just by learning their native language.

And then there is China - remember that IOI for instance accepts 4 people from each country.

After all it all comes down to individuals. In Poland, there is famous informatics high school teacher who is credited for producing most IOI/IOM medalist per high school pupil in the world I believe.

They have special training program there. Another thing is to actually find geniuses, obviously. And if you don’t believe in geniuses, meet Jake - https://m.youtube.com/watch?v=OR36jrx_L44

For example, Jakub Pachocki (director of engineering of OpenAI) who graduated this high school, actually was on the verge of getting F from maths in his previous high school, because of problems being to easy I believe. Then they made the transfer where he could finally thrive. Interestingly, he wanted to do phd in 2 years in University of Warsaw, but people there didn’t want to allow it just because so they lost him - he went to do his PhD at Carnegie Mellon.

To summarise, from what I understand formula would be something like genius + great, inspiring and allowing teacher(s) + special personalised teaching programs + supportive environment.

Also don’t assume that these outliers are testament to the level of education of general population.