It IS pathetic, the more so because I don’t know what can be about it other than perhaps isolation and “deprogramming.” Like any cult they reinforce each others’ delusions, and the delusions themselves are self-reinforcing: all contrary information is a product of the conspiracy against them and further proof that their delusions are real and conspirators are out to get them. I’ve seen these kinds of conditions described as “strong but brittle,” in that the victims defend strenuously against any contrary information because any that actually gets through is liable to shatter the entire delusion. (And then of course the family gets to help pick up the pieces.)