Because killing the Jew is the devil's only chance. He looks at it as his chance to win. If he could kill all the Jews, God's word would be broken. God said he would save a "remnant" of Jews, seemingly 1/3rd of them according to a few passages. IMO, DNA testing will allow the devil to "make war with the remnant of her (Israel's) seed".
The Jews pronounced a curse upon themselves until the end of time when they corporately rejected Christ at the Triumphal entry, and then said "Let his blood be on our heads and on our children" when they crucified him.
They're blinded and will be until the end of the age. Yet even then, some find the way. Throughout history, Jews have roamed from country to country, looking for refuge, always hated.
As for why people hate them now, Christ said that satan was the "god of this world". Most people have - unwittingly - made him their god. The children of God will do his bidding, just as the children of the devil will do his. Why does that hatred manifest itself? My suspicion is that it's because, by and large, Jews are smarter than us gentiles. Look at the head of corporations, law firms, accounting firms, hollywood studios, banks.....Jews dominate many industries, considering they are a tiny % of the population. They have the blessing given to Abraham, though still cursed by God.