I was born into a cult, which collapsed in 1982, when I was seven. I eventually wrote a novel that drew from the experience, entitled Children of the Folded Valley.
The number one question I'm asked again and again is why did people fall for it? The answer is complicated, and has to do with the frog-slow-being-boiled-alive principle (ie, a frog will leap out of boiling water, but will sit and be slowly boiled alive if the heat increases gradually). Cult leaders target lonely, vulnerable people with particular backgrounds and psychological make-up, and once they have people under their deceptive sway, it can be incredibly hard to break out from under it. Even when cults collapse, adherents can remain in a state of adamant denial. At the risk of getting political, what is happening in huge swathes of right-wing America right now is an example.