Context of Jewish Problems

These things happen more than once, many more. Here are some remarks on the reasons.

Europe in the 14th and 15th Centuries - some context
The bubonic form of the disease was a bacterium (Yersinia pestis) spread by fleas from rats. The pneumonic form of the disease spread from one person to other people. This was made worse by crowding in the cities. Some cities lost from half to two-thirds of their population. Some small cities became ghost towns. Common folks were dying as well as the most pious. Perhaps a third of the Catholic clergy died, with priests who attended the afflicted being hit the hardest. The poor were hit harder than aristocrats because they were generally in poorer health and less able to resist the disease and because they were more crowded together. Wolves fared better and appeared in some capital cities.

People did not understand the source of the plague, and panic spread faster than the disease. The belief in witchcraft was revitalized. Believing that the end of the world was at hand, some groups engaged in frenzied bacchanals and orgies. People called the Flagellants believed that the plague was the judgment of God on sinful mankind. They traveled the country, men and women flogging one another. They preached that anyone doing this for thirty-three days would be cleansed of all his sins -- one day for every year that Christ lived. The Church was still on guard against innovative religious proclamations, and in 1349 Pope Clement VI condemned the movement.

The wandering mobs focused their wrath upon clergy who opposed them, and they targeted Jews, whom they blamed for inciting God's wrath. In Germany rumors arose that Jews had caused the plague by poisoning the water. Pogroms followed. Jews were arrested. Their fortunes were seized by the lords under whose jurisdictions they lived, and Jews were put to death by burning. The attacks on Jews were condemned by Clement VI, and he threatened excommunication for those Christians who harmed Jews.

 

JEWISH MONEY AND ECONOMIC INFLUENCE
A view from Werner Sombart who was a German professor of economics. He thought that capitalism originated from an earlier tradition than Christianity and that it was more a Jewish construct. He was published in 1911 and  not challenged at the time. He says of them that:-

   *  They were foreigners with no formal citizenship everywhere in their

                diaspora.

   *  They were scattered throughout the world, never concentrated

                in a single area.

   *  Their physical and social separateness from non-Jews was voluntary

                and part of their religious world view.

   *  They were not peasants and were not linked to the land in their diaspora;

                wherever they were found, they were an urban class.

   *  They lived a double standard of morality: one for themselves and

                 another for non-Jews, which functioned to position them as

                 intermediaries between other peoples, and ultimately protected

                 their group solidarity and identity.

   * They had strong injunctions to marry only within the Jewish community.

                 [TRAVERSO, p. 44]  

    * They also accumulated "liquid wealth," per merchantry and

                 money lending enterprises.

At least some of this is beyond dispute. They may feel disposed to object to the rest. That does not mean that he is wrong.