i cant really think right now. but i do believe that stereotypes are mostly true
A stereotype is a generalization of an entire group. It's either true or false, not mostly true. That's what separates stereotypes from statistical trends. The problem is when you assume something about someone else because other members of that person's group (or group you perceive them to be part of) often have that characteristic.
But often things that were
believed to be statistical trends among groups were way off the mark and greatly debunked. All sorts of things about what women are rarely capable of doing, for instance. When all you think in is stereotypes you tend to only see people as fitting those stereotypes. And when society at large is pushing those stereotypes people are denied opportunities to act outside of them.
When it comes to Jews, one of those prevailing stereotypes is that they're all part of a secret organization that controls everything behind the scenes to their benefit and everyone else's detriment. I hardly think that's a reflection of truth but a rumor started from a gross misinterpretation and fueled by people who have no problem accepting rumors because they must be based on something. That, and a healthy amount of animosity.
Don't underestimate mankind's ability to get things incredibly wrong on a large scale. At least most of the world's religions most have.