I do think that there is some sort of mental aspect to it for a lot of people though. Not like mental illness exactly... but I know a flat-earther and his life is sort of a stressful mess. I think that this explains for a lot of people why the world is fucked up and their life is not going the way they wanted. If everything else is messed up, it surely isn't them doing anything wrong. It feels like sort of a coping mechanism. I'm sure it's not like this for all flat-earthers, but I only know one.
There, he appeared to not have access to the medical care he needed and started making videos and blog posts about all the fake and forged events in the world from moon landings to Gaza blockades, settling on a flat earth. I received many messages and links from him about how he’d ‘busted it open’ and ‘figured it out’.
This continued for many months, becoming crazy abusive to his friends and associates before it all ended with him taking his own life.
Not suggesting all flat earthers are mentally ill, of course.