I had a feeling somebody would quibble with "independent." In context, I don't think it's a high bar. If we're talking about sex workers, we're not talking about people with regular jobs so work is tied to their healthcare. "Independent" has to mean no more than an independent-minded personality; exactly the sort of person who can cope with running their own business doing something that's less socially acceptable.

Therapy is not the universal requirement for mental health that many people seem to think it is. Most people just muddle through and manage to stay reasonably sane without developing substance abuse disorders. In many cases that might not be optimal, but it's not insane or drug-addled either.