I'm curious why you seem to have such a problem with people who hit a bottom point in their lives?
Everyone has a bottom. For some it may be more severe then others but the plain and simple fact that someone wants to overcome burdens in their life should be a good thing. Personally I could care less if it comes through a belief in God, worshiping a rock or becoming a vegan and swearing off of milk.
The only problem I have is when someone uses their "born again-ness" to try and convert others.
BTW, at work we have two preachers who both run Evangelist bible churches. I asked them both about your thoughts that people like them must have hit rock bottom somewhere and both of them told me nope, they just found it to be the right way to go in life. Neither one of them are ex-drug addicts, sex abusers, alcoholics, or had any other vices...they just felt compelled to go that way.