With regards to why people are inclined to believe conspiracies, here's an article asserting that it is (at least in part) human nature:
>>>“To one degree or another, we all have a disposition within us to view events and circumstances as the product of conspiracies,” says Joseph Uscinski, PhD, an associate professor of political science at the University of Miami. “If we have this disposition very strongly, then we will turn to a conspiracy as the explanation. Generally that explanation will accuse people we already don’t like.” Uscinski has a sea of data to back up this claim, and to show that conspiracism may be no more common today than ever — that in fact America was founded on a conspiracy theory. . . . There’s very little difference in conspiratorial tendencies based on liberal or conservative leanings, and likewise very little between Democrats and Republicans. That’s not to say ideology doesn’t play a huge role in conspiracy thinking — it just isn’t a good predictor of a person’s tendency to believe. <<<
The author gets into Qanon later in the article.
As I see it, if there are multiple explanations that are consistent with a given set of facts, people tend to latch onto a possible explanation that is consistent with their views without really considering whether or not the evidence points most strongly to that particular explanation (i.e. they don't really consider whether or not the explanation they've chosen to believe is the most plausible explanation). I would argue that conspiracies are just one form of confirmation bias.
Who believes and why, and whether conspiracism is really getting way worse
elemental.medium.com
