Kinda like the little kid on the playground who, out of fear and the hope of currying favor, feigns frienship with the kid who bullies him when the teacher comes to find out what the problem is.
There's something to that,when it comes to Jews - but it's not just American Jews. There's a cultural trait of masochism and self-hatred among us, that developed throughout the centuries after the Diaspora. Psychiatrists have long recognized it in Jews, and you can see it reflected in the rabbinical scribblings of the Middle Ages.
It's a developed trait, though, not a congenital one, I think. One of the Roman Emperors (Caligula, maybe?) had to dispatch troops to Greece to quell an uprising when the Christians and Jews started quarreling, and the Jews took up arms and took to the streets. (Ah, those were the days...)
I think the Diaspora had a lot to do with it. The Jews found themselves in relatively small groups surrounded by Gentiles who they could not safely piss off. So any anger and rage had to be redirected internally. A couple millenia of that would make it very ingrained