How can we account for the link between race, income level and conspiracy theories? Theorists tend to show higher levels of anomie - a general disaffection or disempowerment from society. Perhaps this is the underlying factor that predisposes people more distant from centres of power - whether they be poorer people or those from ethnic minorities - to believe in conspiracies.
The more fundamental problem, beyond anomie, is unscientific thinking, and the tendency of people to just want to win arguments. People get emotionally invested in a factual position, and for or against, they'll latch on to whatever they can so they don't have to let go.