The stereotype evolved because Jews were forbidden by law from owning land in most of Europe and also forbidden from joining the guilds that ruled the professions. So if you can't own land and can't be a professional and also might be forced out of your home in a hurry, the game-theoretic solution is to be a moneylender. I don't think this is particularly cultural, as women in India for instance have long kept their wealth in gold for the same reason. That's why women like jewelry: if you're forbidden from having a bank account and credit and can't own your home, you need to have something you can carry away and pawn. (I mean, since the 1960s women have been allowed to open their own bank accounts in the US -- but that's within my mother's lifetime!)