https://en.wikipedia.org/wiki/Confirmation_bias
Why people join cults
“Cults form and thrive,” says Deikman, “not because people are crazy, but because they have two kinds of wishes. They want a meaningful life, to serve God or humanity; and they want to be taken care of, to feel protected and secure, to find a home. The first motives may be laudable and constructive, but the latter exert a corrupting effect, enabling cult leaders to elicit behaviour directly opposite to the idealistic vision with which members entered the group.But cults, because they only serve the leader, exploit and pervert that useful habit and, to establish and maintain itself, does everything possible to destroy family ties, and any other secure and conventional anchor in a person's life. This has the effect of strengthening a member's bond with the cult and its leader. From this viewpoint, the cults that promote celibacy and the cults that encourage indulgence in sexual promiscuity are seeking the same ends — the destruction of normal family life and the substitution of dependence on the cult group authority. Although ordinary institutions in our society do not yet directly seek to destroy family ties, 'nanny state' interference may be having a similar effect.