I was going to post this in the movie thread, but I just watched 'Behind The Curve' a flat earth documentary on Netflix.
It's a bit too lazy to just say these people are batshit crazy. It's not that they are unintelligent or mentally ill, it's more like an indoctrination, or even something along the lines of narcissistic personality disorder. It really is like a new religion, and like any religion, when you believe hard enough in it, then you have all the answers and you can't be argued with.
It's just sad, it's not as if these people are evil or anything, just completely lost which is alluded to in the documentary by the various physicists and psychologists.
It hits home a bit because one of my oldest friends has lost his mind completely, we hung out last weekend in a mate's gaff and while flat earth didn't come up, he's basically a born again Christian, who believes we are in a spiritual war against the Satanists. He's highly intelligent and a great musician, but it's fascinating to see someone like him buy into literally every conspiracy, and even though I am interested in various topics he brings up, he gets aggressive when I point out something is complete bullshit and it's just impossible to argue with him.
It's gotten to the point where our other friends won't even show up if he's going to be there. Jews this, Freemasons that blah blah blah. I left in a huff because I couldn't listen to him anymore. I'm getting too old for this shit.