There's apparently a dispute on the alt-right about whether or not to hate the Jews in addition to blacks and Hispanics and Muslims and such.
The argument for hating Jews is basically because when you think about it, in the US, blacks, Hispanics, Muslims, and such really don't have the economic or political clout to make things miserable for whites. So if the conspiracy theory's going to hang together, there needs to be another group to which such clout can be attributed that's manipulating everything behind the scenes, and the Jews are (as they so often are) the most convenient scapegoat.