system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Holocaust deniers, how and why do they deny it ?
gpt
For some, the rationalization is that they see some sinister Jewish shadow conspiracy to control the world, and believe that all claims related to the Holocaust are falsified in order to further the aims of that Jewish conspiracy.

The more "not stupid" version, is simply people who believe that the reports associated with the Holocaust, particularly the numbers of the slain, are inaccurate or exaggerated, or that reports of outright mass-execution and actual extermination were overblown. Some just don't want to or can't accept that such events happened, because it says very uncomfortable things about what humans will do or can be coerced to do under the right circumstances.

Sadly, as horrible as it was, the Holocaust's reality was fairly well-documented.