Community effect Group think plus Confirmation bias plus Halo effect – a result in the subject being held in higher and higher regard leading to theories believed for their own sake and organizations that exist solely to perpetuate themselves. Positive death spiral creates cults, negative hate groups.

An affective death spiral (or happy death spiral) occurs when positive attributes of a theory, person, or organization combine with the Halo effect in a feedback loop, resulting in the subject of the affective death spiral being held in higher and higher regard. In effect, every positive thing said about the subject results in more than one additional nice thing to say about the subject on average. This process creates theories that are believed for their own sake and organizations that exist solely to perpetuate themselves, especially when combined with the social dynamics of groupthink. Affective death spirals are thus a primary cause of cultishness. The same process can also occur with negative beliefs instead of positive, leading to a death spiral of hate.

– Lesswrong wiki