I find some conspiracy theories (e.g., Sandy Hook, 9/11) utterly contemptible and some hilarious (flat earth, the non-existence of Finland), but I think the psychology behind them is fascinating. Not long ago I read an excellent book about the Salem witch trials. The writer enumerates the genuine dangers and threats the colonists faced: wild animals, harsh weather, unstable government, raids by native Americans, war and the rumours of war. One would think that these perils would be more than enough to cope with. And yet, the colonists became caught up in a collective hysteria about witchcraft, accusing their neighbours, friends, and relatives of being witches, including children as young as five (and some dogs as well).
Why did it happen? For many reasons, of course, but I think one reason was that the real dangers were so enormous, so terrifying, and the colonists were essentially powerless before them. So they sought out an enemy they could fight against, a menace they could assert some control over. Certain people became scapegoats: nineteen were executed and hundreds accused. The spiritual threat could be contained in a way that the actual, physical dangers could not.
I think quite a few people buy into contemporary conspiracy theories for similar reasons. It may be comforting to believe that a sinister group of individuals is in control behind the scenes, plotting and planning the operation of horrific events, rather than to accept that the world is a complicated, messy place without a centralized locus of control. Conspiracy theories allow them to order the world in a way that gives the illusion of control. Madmen enter schools and murder children, and it may be easier to believe that there is some reason such tragedies occur (or to deny that they even occur), rather than to admit that we live in a world where terrible things happen for no reason at all.
Added to that, conspiracy theorists tend to feel a sense of empowerment and superiority, because they are convinced they know The Truth, and they can scoff at the “naïve” individuals who are too blind to see what’s really happening. The idea that some cabal of grey-suited men are in control is just a short step from seeing a coven of cackling witches as the source of all misfortune.