I think theirs a variety of reasons Jews were hated and still are hated.
Much of it I think was originally religious, when Jews first entered Europe, it was mainly Xtian and many people blamed Jews over the death of the Xtian messiah. Of course this spanned long wars and the whole crusade period. Also lets not forget many people who are critical of the Tanakh. Some of this come from Atheists who are against what the bible says.
Racial, I think some of it is racial as well. Many countries trying to get rid of ethnic minorities felt Jews were a threat because they did not assimilate but yet were successful in the countries they lived in. Also some of these movements like "Black Hebrew Israelites" who proclaim to be the original true Jews, the British Israelieans, the Christian Identity movements, and all these other groups who claim to be the "true" lost tribes of Israel and associate Jews as being related to the Khazars?
Political, unfortunately a large number of those who are considered Jewish tend to take left wing politics that work against a countries interest, we see this today in the US with those we don't even consider Jewish because they are not Orthodox or the way they behave. Unfortunately many people attribute Jews (in specific left wing) to communism, running the banks, globalism, etc and feel that Jews are responsible for what is currently happening in the world with the New World Order. Some of it is also hate for many Jews support of Israel or the Zionist movement feeling that Jews are loyal to Israel over the country they live in.
These aren't my views, just what i've gathered over time from the 'reasoning' behind peoples hatred of the Jews. It's really a complicated mess.