The question is, why do they hate us so much after we saved them in WW2?

Jews are prejudiced towards non-Jews, and have been since Old Testament times.

This is the normal state of humanity, all groups are prejudiced against one another and promote their interests at the expense of others.

Only white Christians have made a real effort not to be prejudiced in this way. And the result is whites being attacked (culturally, physically, demographically) as a soft target who don't defend themselves.