Exactly fiction vs science fiction, i see no difference. At least we know the author that wrote the later one and aren't blindly hoping some guy we will never have proof of wrote the other one thousands of years ago.
Simply the age of the bible and the fact you hear about the "normal" religions from day one are the only reasons you become accustomed to hearing the stories/idea's and find them slightly less ridiculous, in reality its the same. Any odd thing you hear once heard enough starts to seem normal if you see what I mean, doesn't mean it is though.
Either way, I would imagine a lot of stupidly rich people have kind of gotten to that point in there lives where, frankly, they can smeg off to an island and never see anyone ever again should they not choose to. Once you're set for life, you're set, some people drive for more success and obviously some people will start to ask the question, what the hell next? Some people will inevitably feel like they'd done what they set out to do, they know how the rest of their lives will go and what they'll do and they start to wonder if theres something after it, or if theres a way to make sure, etc, etc, etc.
Cruise seems frankly nuts these days, and for a long while, its also unsurprising that some stars have issues, mental problems maybe, depression from feeling isolated? Imagine being as rich and famous as him where everyone knows him, you could easily (and maybe rightly) start to believe anyone thats ever nice to you is simply trying to get something from you, hard to have real friends or a real life with privacy. Scientology is for those people a rich club of people all looking for the same thing out of life, looking for the same answers, maybe you'd find someone who feels the same as you, can be friends and aren't looking to get something from you, I'm talking about other people who fall into it rather than those who run the thing.
THe ones that run it like any other nasty people are just looking to take advantage of troubled people who more than likely have problems in their lives or are depressed. Meh, if it gives say Cruise an outlet and makes him happy, what the hell does it matter. in a hundred years when everyone has learned of scientology from a young age it will become more accepted. In 500 years no one will remember/believe the early stories of where it came from and people will accept it as a real religion, just like the others.