It's not about believing everything or nothing, I think: it is more about how to filter things you believe. Believing something is a way to be part of a group,

It's not about believing everything or nothing, I think: it is more about how to filter things you believe. Believing something is a way to be part of a group, and it seems to me that most humans (including me) tend to feel better when they are recognized as a part of a group. Conspiration theories offer an easy way to feel part of a very well identified group (made even stronger by the sensation of being a somewhat repressed minority): for some people this can be much more rewarding than accepting the rigor of actual science.