It does go into the why of it, and very deftly at that. Because the eight people who are the focus of the movie are all former Scientologists, they explore the question of why they fell for it and stayed inside for years. It's both unflinching and compassionate.
Paul Haggis wrote a piece for The Underground Bunker last week in the leadup to the debut of
Going Clear that lays it out beautifully.
The Church is shrinking, no question about it. They keep buying real estate to build "Ideal Orgs" premised on the fiction that they need vast, state-of-the-art facilities to cope with the onslaught of new believers, but it's just a scam to extort even more money from the people they're already bleeing dry with fees for "coursework" and auditing and the forced purchase of whatever latest packaging of Elron's horseshit books. These new facilities, all of them huge and most of them historical properties brutalized into performing this disgusting function, are tumbleweed empty.