Why were Jews and Gypsies slaughtered in World War II?

On the surface, it is racial discrimination and extreme nationalism.

But if there is no huge benefit, it will not turn into a massacre. And it is the Jews who have mastered a lot of wealth. Coupled with the negative image of Jews in history, it eventually evolved into a massacre. This is similar to the historical exclusion of China. The reason is that Chinese account for most of the local wealth, followed by race. As for the Gypsies, they are just fish in the pond. Anyway, Gypsies are homeless groups and belong to social instability.