I think it does attract a particular kind of person (leaving aside the professional career mentors and advisors etc) because - unless you have aced life in every way - you need to have a certain lack of self-awareness to think that you can tell other people how to "do" life in general. It just sounds so arrogant, or maybe that's just my Calvinist roots! - but having fucked up this and that like most people, I'd just feel embarrassed to announce myself as a "life coach". And yet my life is nowhere near as chaotic as those of "life coaches" I know.
BUT I was thinking about this thread and there's another thing - a patriarchy thing. 99% of the people who are looking for these new careers are women, mostly women with kids who have been edged out of their careers or just given up because it was too exhausting being the primary carer and trying to hold down a job. They do that because of crap from employers, laziness and refusal to share the load from male OHs, and societal expectations that mums (yet less so dads) should be "there" for their DC.
Then they end up needing part-time work or wanting to work around DC and school hours etc - and become easy prey for all manner of MLMs, home-selling schemes, training courses that promise to relaunch you as this that or the other. So many female friends and acquaintances have done the whole "I'm retraining as a..." life coach, massage therapist, doula, yoga teacher, interior designer, osteopath, etc etc and then almost always it doesn't work out and they're onto the next idea.
Part of the problem is that people get starry-eyed about being self-employed and don't understand what it really involves. I've been self-employed most of my career and it's hard, hard work and you need to be organised and committed. £50 an hour to coach or massage someone sounds great until you realise you're not getting that every hour, you have to find clients, you have gaps in between, you have no holiday pay or sick pay, and maybe you're not as good as the experienced competition.
I think employers should be required to offer part-time jobs that fit in with school hours, for everyone (and not make this about women and mums) wherever possible - obviously there are some exceptions but many, many jobs at all levels could be done this way.