Genuine question, not a jew lover or hater just totally ignorant to the issue.

I was watching a YouTube video listing the top 10 people who had dark sides / beliefs.

It was showing Ghandi saying that Hitler wasn't as bad as made out to be and that Jews were better off killing themselves.

Like what is the cause of so much hatred to one race, I'm not racist but I can't help but think that when this re-occurring theme keeps popping up, the hatred must stem from somewhere?