This just goes to show that Trey Parker and Matt Stone are prophets, and their show, South Park is prescient!
Does anyone remember the episode "Jewbilee?" That was where "Elder Garth," from the "Synagogue of Antisemitic Jews" tried to usher in "The Reign of Haman."
On a more serious note, some of the worst oppressors of Jews in history have been people who were once Jews (or had Jewish ancestors), and rejected being Jewish. Examples would include many involved in the Bolshevik revolution and ruling the Soviet Union. And of course, there's been the rumor for many decades that Hitler had some Jewish ancestory.
For a less virulent version of this sort of thing, one can simply look at militant anti-smokers.
Mark
One of my all time favorites!