By the way, why did Nazis murder millions of Jews and Gypsies and Poles?

Well, Hitler believed that he could create one master race by eliminating the imperfect people. This included Jews, Poles, Gypsies, people with disabilities, ect. He believed a perfect person had blonde hair & blue eyes. (He didn't even have blonde hair & blue eyes himself, mind you). He thought a "perfect Germany" could be created with the elimination of these groups of people.