The holocaust was a terrible horrible event and the fact that it happened is disgusting. However, Hitler did a lot of (inhumane) scientific experiments on his victims. Would we be where we are now in the medical and scientific worlds without those experiments? If not, why?
While more can certainly be said, u/commiespaceinvader did a wonderful write up on if the Nazi's human experimentation actually discovered anything of value here, which is no, no it didn't.