From what Nightwolf told me and from research we did for novels set in Germany in the 14th century - the "Jewish" problem was very easy for Hilter to exploit because the basis of it went way back, pretty much to the late Migration Age/Early Middle Ages.
While the reasons are rather complex, the most basic issue in Germany, England, and other areas of the former Western Roman Empire was that local laws (and the Catholic Church) forbid most Jews from working in most professions and this got worse as time went on.
In the early period, they were often merchants, something that never totally stopped but therefore would appear to many people to be wealthy. But the main issue was that "Christians" at the time (which most people were considered to be) were forbidden by law to engage in "usury" or to "loan money." Of course, that did not stop a need for some sort of banking, especially on the part of the nobility.
I mentioned in the Crusader thread that nearly every time a powerful King or extremely powerful person(s) had borrowed more money than they wanted to repay or often could possibly repay, there was often an attack on the Jewish community. This happened over and over and over again, often accompanied by mass murder and "explosions" of the Jews from various Kingdoms, Fiefetoms, and Free Cities.
Over time they would be invited back, usually because the local grandee needed money again; later the Knights Templer also got into the banking game and eventually were brutally disbanded with their leaders burned at the stake when the French King decided he needed their money. There's a long story there as well, but that perhaps is better on another thread.
Bottom line, as Nightwolf said, it was easy for Hilter to get the non-Jewish Germans to view Jews as "Other" because for centuries they had often been viewed that way already. Maybe not to the same degree of hatred as there had been in the Middle Ages, but all Hitler and Gorbals had to do was reignite the old fears and underlying beliefs of many people that Jews were somehow "subhuman" even if by 1930 most people wouldn't have said it in public. Until the NAZI party made it acceptable to do so.
