Tbh, life coaches generally market towards specific targets, like "how to get the job you want", "how to organise your finances", "how to be successful in xxx hobby / study / career".
The idea is, set a goal and they will advise on practical "tools" as to how to achieve it. Mostly they teach common sense, or organisation skills, to help someone direct their thoughts to achieve whatever their "goal" is.
Theoretically their methods could be applied with ctb in mind (though you couldn't ever actually tell them that was your "goal" 

). Irony there… seeing a life coach to practically implement cbt. 
I do think they're generally taking advantage, but people will pay for anything these days. Also some people just like being told what to do, and they cash in on that. 
Generally they cannot and should not take clients who are struggling with mental health disorders with their "goal" being to overcome, because they're not qualified. You can get a "life coaching certificate" by doing a crappy online course. 
Sorry if any ones a life coach, I just think it's mostly a crock of ****