It wasn't flag football or nerf that got us to the top.... We literally dominated everyone in everything, and continue to do so. Whether it be the military, sports (we just got done dominating the Olympics), tech, whatever.
It's absurd to think that given societal collapse, it would be the American's that struggle the most, and not, you know, the people that can't even make it when times are good...
You can knock us with a bunch of made up criticisms, like "emotional fortitude". But at the end of the day, every country still bends the knee to our "physical stamina". So that doesn't really say much about the rest of you surviving if conditions took a turn for the worse.