US pool is also smaller than it seems. US doesn't have world / 8B to draw from, it has ~1B English speakers where 400-500m where EN is primary, another 600m where English is proficient. Shared with other advanced economy / Anglo institutions. Vs PRC has 1.2B Mandarin. US pool is also immigration gated, even with PRC's shit TFR, PRC will still knock ~2x new births for the foreseeable future vs US 3m newborn+immigration... and PRC can push that 6m disproportionately into STEM.

But PRC's actual talent pool is their 20 year back log of 10-15m per year births (100m+) that hasn't gone through tertiary, i.e. about another 40m+ STEM assuming they don't increase tertiary enrollment (currently 60%) or tertiary (40%). The worse case scenario for PRC is they will have ~OCED combined in STEM (not including other tiers of technical talent), or 3x+ more than US, assuming US pre Trump immigration patterns.