Probably they are gaining power/wealth not proportional to their numbers in the society they live in. That happens easily when a close knit society works hard while trading, doing business among themselves (e.g. buying goods and services from in-group rather than outside when they can) as well as favor community members over others in the larger society. This probably creates hatred of the majority towards Jewish people and that hatred directed more at times of distress like economic hardship or wars. I heard today that State of Alabama passed an immigration law recently that target immigrants. Probably people in Alabama do not want immigrants these days, since they are seen "stealing" jobs while jobs in US has been vanishing since 2008 economic crisis.