What amazes me is that people who must have something going for them to get to where they are in life -- John Travolta, Tom Cruise, Beck, etc -- seem to have swallowed said crock of shit whole.
Having grown up in a Mormon family, I have first hand experience with the same sort of cult. The founder of the LDS Church, Joseph Smith, was also a charismatic con artist. If you look at any sort of historical accounts aside from those the LDS church puts out, this is pretty non-controversial. And once they got to Utah, they did all sorts of crazy things. Yet now, the Mormons are regarded as a more or less mainstream religion.
And yet, there are plenty of sincere people who have unswerving devotion to both LDS and Scientology. Hell I've no doubt that a lot of people's lives have been improved by joining those Churches, and a thousand others. It could well be that all the world's religions are nothing more than cults started by conmen, and what separates the cults from the religions is longevity.
It's enough to make you think that believing in something -- no matter how improbable, slip-shod, or loony -- improves people's lives. Of course, it's demostrable that it ruins other people's lives at the same time.
Of course Scientology is patently full of shit. The enmity between Scientologists and Psychiatry is a perfect example. While psychiatry is not above criticism, there's certainly a body of work that has been done since the time of Freud that stands up better to criticism way better than Scientology.