The problem is that the 340 million people there are incredibly diverse. While a large part would circlejerk about how superior they are, another large part wouldn't. It's easy and fun to lump all Americans together, and even mandated by our brains inability to process such large numbers, but doing it always unfortunately alienates the ones that do not exhibit the traits you ridicule.

It's so much better (and useful) to just ridicule the traits/behaviors themselves instead of the relatively unrelated nationality. There's nationalists and smug superiority everywhere.