Bad guys don't think they're bad guys. Hitler probably thought he was a wonderful guy doing some wonderful and righteous work for Germany.
“I always loved Kate Winslet, but after you meet her you really love her because she's a cool chick.”
“My other brother, the Lord Lucas, who was heir to my father's estate, and as it were the father to take care of us all, is not less valiant than they were, although his skill in the discipline of war was not so much, not being bred therein.”