Many reasons. But mainly, it's because there has been some proof of jews dominating and owning many important fields of the world, and the stereotype that jews are bankers, accountants, financers and that they love money. Also the israel-palestine conflict. These ideas make people think that jews ultimately rule and own everything since the Rothschilds and that they are trying to destroy the white race with their power and occupation of the world. Sorry it's a bit of a crude explanation but i'm sure some other chuddy in ITT can explain way better than me doe.