In the video that I embedded in my previous comment, this young Brit says that out of the thousands who watched his miniseries about the 9/11 attacks, only one stopped believing in conspiracy theories. That is precisely the experience I have had with people I met in a New Age cult and parapsychology: the vast majority are impervious to the evidence.
The pathology of belief is a topic that goes beyond the limits of this site, although I have talked about it in my books written in my mother tongue. Simply put, the astronomical delusions represented by religions, paranormal pseudo-sciences, and even secular ideologies (feminism, anti-racism, idealising sexual deviants, etc.) have nothing to do with reason and good judgment. It has to do with self-esteem, self-image, groupthink, and the defence mechanisms we develop in the face of a cruel world.
The subject is huge, and just as Oliver Sacks used the biographical narratives to illustrate the symptoms of right-brain injuries, only an autobiographer who has rid himself of one such false paradigm could illustrate how the psychology of self-deception works.
By the way, in my post yesterday about truthers I made a couple of minor mistakes that I just corrected. One of them was a link to the wrong article about Ron Unz. It is worth rereading the right article, including the discussion thread.