Interesting thread, particularly like polyglot's first post.
I'm on the verge of stepping into portraiture with a bit of freelancing in mind, and with much trepidation - perhaps partly because I'll be shooting digital primarily. I'm also surprised how many professionals are clearly doing very well without any sense of composition and in a lot of cases, very poor aesthetic judgement in post-processing. The thing is, clients are obviously happy with the results and with business in mind, any sudden self-awareness (in reference to Dunning-Kruger effect) might leave them struggling to pay the bills. Being as competitive as the game is, anyone with creative drive might ask themselves "why bother trying so hard?". A strong mind for business seems to be much more advantageous - is business 'vision' art? People who champion Apple seem to think so.
There are a few videos on YouTube by a successful photographer, Zack Arias. His insights are very informative, but I have to say, despite his criticism of many in his profession, his own work is pretty middle of the road. But perhaps I've spent too much time as an amateur aesthete. A big reason for my wanting to get into portraiture is the work of David Eustace which is so classic, simple and unaffected and about a million times more artful (I didn't say 'better') than Zack Arias. See his 'Character Project'. He started in his early 30s, after working as a prison warden in Glasgow! Surprising how many people get into professional portraiture as a dramatic and sudden career change. This seems to be getting more common with entrepreneurship becoming so celebrated in the current economy.