Also, the term “baalei teshuva” includes a very broad range of people. How likely they are to revert back really depends on the individual and the individual situation. Some people were coming from nothing to begin with and others grew up fairly traditional and had a Day School education. Some just recently became Frum and others have been Frum for a long time.
The factor that would make the most difference is: How grounded is the person, both in general and in their Yiddishkeit? Is he/she a rational person who made his decision based on rational reasons?
I know a baalas teshuva who became a christian missionary, but knowing her, I wasn’t as surprised as I might have been. She was very spiritual, but she had never been well-grounded. When she dated someone Chareidi, she “became” chareidi and switched her kids to a chareidi school. When she later dated someone dati-leumi, she became dati-leumi and again switched her kids’ schools.
I do understand your point, Abba about spiritual dangers being greater. I am just making the point that my impresion (although I’m not an expert so I may be wrong) is that it is impossible for any addict to ever be out of danger of a relapse, and a relapse has a very good chance of being deadly.
On the other hand, with baalei teshuva, my impression is that the chances of a relapse are much more minimal in most cases (each case is different and has to be judged for itself, but with addicts, I think it’s a given that the danger of a relapse is always grave – no pun intended – it’s not very funny anyhow, but unfortunately holds a lot of truth).
But again, I am far from an expert, so my words should be taken with a grain of salt, but it would be a good idea to research the matter.