The locals who’ve been exposed to the prevailing conditions(extreme cold, lower oxygen saturation) their whole life, and who passed through the evolutionary gauntlet of the region (higher chance of genetic material with weaker lung capacities to die out), might have been hardier than the wave of rich tourists who later conquered the peak.

All this is speculation though, based on the fact that people that live in such conditions their whole life DO have demonstrably better adaptations to do so. I don’t know if it’s enough to survive the conditions at the peak though.