I think this 'good vibes only' aspect of US society is a side-effect of the country being only a few hundred years old and never having dealt with any real existential catastrophe. 9/11 is probably the closest thing to one the US has undergone, and I don't think the country has handled it that well.
Edit: I considered the Civil War, but internal strife is simply not the same as an external/natural disaster that overtakes the whole country.