It's all a matter of perception. We've got our fair share of assholes, too.
I have visited the US many times. I can't recall
any unpleasant encounters with Americans.
Actually, there
was an incident in Papa Joe's bar outside the gates of Roosevelt Roads many years ago. A Seabee deliberately drove his shoulder into my back as he walked by. Yadda, yaddah, yaddah...the entire place erupts into a brawl. When the dust settled, I stayed, he was punted from the bar.
Other than that, it's been all good.