I agree they are dissatisfied with something missing in their lives.
I have workmate who is antivaxxer, thinks mainstream media lies and that most diseases could be cured with just good nights sleep and healthy food.
Yet he had all mandatory vaccinations and admitted that he would go to doctor if he ever got sick.
He is 30, healthy, no kids, not very highly educated, but makes good money.
Everything he is against doesn't affect his life one bit, its like hobby to him and it gets good reaction from others.
His conspiracy theory articles can be debunked in few minutes and then he throws in even bigger article and he hasnt even read those, so if you keep pushing he has nothing to say.
There's usually an explanation for this, though it may not be immediately apparent.
But typically the person feels like they have no control, so inventing this universe that makes sense to them allows them to retain some (fictional) control. Or they may feel worthless or low-status, and if they imagine they "know" things that most people "don't know" that would restore them some of their perceived status. Or they may completely disagree with how the world looks like and the direction where it appears to be going, so let's invent this other world that's more satisfactory.
I mean, if all of the above (and similar) explanations fail, you'd just have to assume the person is not very intelligent. I'm not sure what else could possibly explain it at that point.
Everything he is against doesn't affect his life one bit, its like hobby to him and it gets good reaction from others. His conspiracy theory articles can be debunked in few minutes and then he throws in even bigger article and he hasnt even read those, so if you keep pushing he has nothing to say.