There must be a better term for this than "conspiracy theorist". If you believe the official 9/11 Commission report, as I generally do, that qualifies you as believing a conspiracy theory in any intellectually honest meaning of the term (a theory about a conspiracy.)

The term seems to have entered the general public's lexicon in the aftermath of the Warren Commission report, which was decidedly not a theory about a conspiracy (it asserted that Oswald was a lone wolf, who didn't conspire with anybody.) Disagreeing with that meant you had a theory about Oswald or others conspiring; a literal conspiracy theory. But since then, the term "conspiracy theory" seems to be leveled against anybody who disputes an 'official' narrative, regardless of which side (if either) is putting forth a theory that involves conspiring. All theories about 9/11 are conspiracy theories (unless you can find anybody who seriously believes that all four plane incidents were perpetrated by lone wolves who, by pure coincidence, all chose the same date and methods.) As the term is commonly [mis]used today, it may as well mean "unpopular theory."