Imo holocaust did happen. However another real travesty is what happened after the war with the displacement camps. People who were displaced couldn't just go home and so multitudes of sick starving people were ushered into camps to be re distributed to countries https://en.m.wikipedia.org/wiki/Displaced_persons_camps_in_post-World_War_II_Europe
. This took many years. Many more people died because of those poorly run camps(rampant sickness and disease/suddenly feeding people who are starved risks killing them) and I have a sinking feeling history may have lumped those numbers in with Holocaust numbers