The complexity of social beliefs is that they can be real by virtue of being told, and thus the notion of evidence is entirely connected to our heuristics for common beliefs, and it requires not further evidence.

Some aspects of reality are not directly visually observable. Those are in fact very common in the social realm (while there still are observable aspects of social reality, such as written norms, social behaviors or visual icons).

Some of these aspects are also increasingly common even in the realm of the observable, as our societies super-specialize, we do not access the observable events that might act as evidence.

In this way, parasitic beliefs can evolve far outside the realm of the observable real, and unobservable real, maintaining only a social reality.

These bubble beliefs take on a life of their own, self-evidence, and so long as they do not need to become observable, or manifest in a measurable way for the successful enactment of other events, they can remain useful to a social group.

These useful social beliefs grow, and can eventually take so much space that they become priors over other functional beliefs that do in fact need to manifest successfully.
These eventually cause the crash of the evidence system.

This is what we are observing with the overlap between the spiritual, conspiracy and fundamental religious groups. This is what paved the way to Q.