Turning this around, how many people died in concentration camps due to the fact that they closed their eyes to what was actually happening under the Nazis until it was too late?
A way-back experience for me was in college when a history prof introduced himself with his hefty accent, and said that, like the rumors about him, he was in the nazi youth and the German army during that era. His story was that, as long as it was all about uniforms, camping out and torchlight parades, it was a lot of fun; kinda like Boy Scouts with guns. He would not have to go to one of the other camps.
Once he realized what was really going on, his story was that he found a way to be captured by the British and spent the duration in a POW camp. Somehow, he came to be teaching history in a State college in Baltimore.