You must not know many Jews. My state (Maryland) has one of the highest concentrations of Jewish people in the USA, and only recently have any substantial numbers started to see the wisdom of voting conservative.
Also, many hard-left anti-American intellectuals are non-religious Jews, like Noam Chomsky.
Its somewhat akin to lemmings jumping over a cliff to their death. It makes little sense, considering that left-wing Marxist/socialism (which includes Nazism) is the root of much of the genocide committed against Jews, and anti-semitism has florished in socialist states around the world.