I don't think it's about evidence...
...or truth or even beliefs. I think it's about publicity and attention...writers and filmmakers who are looking for something that'll garner them some press.
They'd need at least a small amount of talent to exist in the mainstream, so they gravitate to the fringes, where creativity is neither expected nor encouraged, and critical analysis is considered a weapon rather than a tool.
They are con-artists who've taken up the pen and the camera. They are an insult to one of America's greatest acheivements.