I can understand how people get caught up in it. When I was with my ex he was involved in a cult like fundamentalist sect of Christianity. I'm not a joiner either. But it's a very systematic way of breaking people down and selling a new version of the truth. You'll see a lot of people who seem like they are lost or who are desperate get involved in these things too because they offer the answers that people want to hear. You know? I watched my ex do it. He got secluded from the rest of society. Was spoon fed this crap day in and day out and bought into it. Doesn't matter how smart a person is or how much they want to join stuff. It's subtle and systematic.
That being said. All people in any culture are brain washed to some degree or another.