|Somewhere between 6% and 20% of the American public
(depending on whose stats you believe) think
the moon landings were an elaborate hoax.
All of us engage in paranoid fantasies from time to time, and some of those thoughts (if they're persistent enough, and deeply believed) can probably be called delusional.
But what happens when a sizable group of people latches onto the same delusional thoughts?
Answer: Sometimes it becomes a political faction.
Alexander Zaitchik, writing in an article called "Patriot Paranoia: A Look at the Top Ten Conspiracy Theories," points out:
Over the last two decades, a far-right conspiracy culture of self-proclaimed "Patriots" has emerged in which the United States government itself is viewed as a mortal threat to everything from constitutional democracy to the survival of the human race. This conspiracy revival — which has been accompanied by the explosive growth of Patriot groups over the last year and a half — kicked into overdrive with the 2008 election of President Barack Obama, who is seen by Patriots as a foreign-born Manchurian candidate sent by forces of the so-called "New World Order" to destroy American sovereignty and institute one-world socialist government.
Zaitchik points to such popular right-wing conspiracy theories as the idea that military research at Fort Detrick was behind the avian flu virus (or the AIDS virus) and that the U.S. government itself deliberately brought down NYC's Twin Towers (and/or nearby buildings) through controlled demolition, in order to begin instituting a police state (with repeal of personal freedoms, increased ease of wiretapping, and mysterious goings-on by a Homeland Security agency tasked with spying on, and detaining, ordinary citizens). To be fair, the latter bit of delusional nonsense isn't just a far-right theory. There are those on the far left who also spout the "9-11 Attack as Government Plot" line of bull.
Being open to bizarre ideas (such as the notion that the moon landings might have been an elaborate hoax) doesn't make you crazy ipso facto. But clinging to such ideas to the point where you're unwilling to consider evidence-based alternatives clearly puts you on a different part of the sanity/insanity continuum than the rest of us. Particularly if you're living your life around the paranoid idea(s) in question.
Personally, I consider the moon-landing-hoaxers and the 9-11 conspiracy theorists to be a bit crazy. Not full-on psychotic, of course (although some no doubt are). But such people are definitely engaging in psychotomimetic thinking. And they live outside social norms. That alone makes them crazier than the rest of us.
The bottom line? Sanity and insanity are not absolutes. They're imaginary goal posts on a playing field that runs the gamut between normal and abnormal. It's a good idea to know what part of the playing field you're spending most of your time on. If you lack enough self-awareness even to do that, look out. Consider it a danger sign.