I've known three people who were in cults while I knew them.
One, a once-popular acquaintance from high school, was convinced she was on the right path, wouldn't listen to alternatives or answer thoughtful questions. I don't know where she ended up.
Another, my older younger brother, has bounced from group to group most of his adult life. He ends up finding something objectionable, leaves, and starts over somewhere else...leaving, in some cases, his living quarters, possessions, furniture, etc. behind. He, too, won't discuss options; my sister is better able to converse with him than I am. He tries to pull me into convoluted theological discussions that he would lose if I really let loose on his lack of logic, but I've held back because he's pretty fragile, doesn't seem like he'd do well if I showed him how he was wrong.
Another, long ago, came to my door to try to convert me. He was himself confused, uncertain and a bit wild-eyed. I ended up de-converting him and helping him find a homeless shelter so he could get away from the cult, which was making him beg for donations and then taking them all. He visited the church I was attending at the time, a couple times, then disappeared. I don't know what he ended up doing, either.
For a couple of years, I was in a campus fellowship that might have had a few cult-like tendencies, but we talked things out whenever they surfaced, and I think we mostly managed to stay sane. I moved away, stayed in touch for awhile, and recently heard back from a couple of other folks who had also left, and stayed in and out of touch. They had a more negative response than I did to it, but we've all moved on to more stable situations.
The thing I learned most from the group I was in, that I hadn't gotten from any of the churches I'd been in, was how to live in community. The thing I had to leave behind when I left was their ideas about married females submitting to their male spouses.
That doesn't work very well if the male is abusive, as I quickly discovered.
M.