Stereotypes aren't just a Jewish thing. Russians are drunks, Japanese are perverts, Germans are ass kissers, French believe in baptizing the wine and the milk, koreans are pinchpennies, Arabs like to smile to your face as they slip the dirk in your back, English are blowhards, Italians prefer discretion to valor, etc etc.
We can play this game all day. Not that it has any connection to reality. A stereotype is what is in your head, not what actually exists. Are there jews out there who are miserly and argumentative over trivia? I am sure there are. Given the conditions of the Ghettos of europe over the last 500 years keeping close watch over the pennies is healthy. And any group of people who are willing to look down their noses at folks who want them to renounce their own stupid in favor of the stupid of the herd around them or suffer the consequences must like being contrary for its own sake.