The thought process of a conspiracy theorist is an interesting thing. Accepting non-verifiable information as facts, accepting info that ONLY confirms their views while deriding anything that refutes it, using highly questionable sources for information, believing that lack of proof of the opposite of their views constitutes proof of their position, total ignorance about fundamentals of math/science/physics, the rabid defensiveness-then-hostility towards anyone who challenges their position. All of these things exist with conspiracy theorists.
Whatever fringe topic exists, there are followers of it, and regardless of the differences amongst people in general, the behavior of the disciples of the lunatic fringe is practically scripted. Flat Earth, Nibiru, 9/11, Mandela Effect, Alien/Nazi UFO bases in Antarctica, Illuminati/NWO, whatever...the discussions are all the same. They know they are right no matter what. Nobody can tell them differently, and if you do, you're labelled a "shill" or a "dumb sheep" or you're accused of "being asleep". Then if you persist, they'll go on the attack and try to drown you in YouTube videos presented as though they are "proof" of whatever head-bangingly asinine topic they think they've figured out the "truth" about.
To boil the whole thing down - people like to feel special and for some, deluding themselves that they have knowledge others do not is the way they feel special. The best thing any of us (those of us who still have somewhat of a grip on reality) can do is metaphorically pat them on the head and send them on their way.