I think the general understanding is that the visceral animosity has to do with the nature of the betrayal. His fund was shopped around largely to other wealthy

I think the general understanding is that the visceral animosity has to do with the nature of the betrayal. His fund was shopped around largely to other wealthy people in his community; they thought they were making money hand-over-fist (particularly for all of the charities and whatnot they could have just been funding directly), with an "in" that people outside couldn't access. Finding out that Madoff had actually lost all of their money wasn't just a hit to their pocketbooks: it struck at the solidarity of their community, at their sense of self and goodness, at their egos. In short, it stripped them of everything that being part of the fund was supposed to magnify. It's not just embarrassing, it's devastating; all of your psychic and material fallbacks have been wiped in one fell swoop. When something like that happens, you don't want to admit that you were taken for a fool; you need a scapegoat, and you need him to be a demon.