Comes from all walks, but some from those folks. Mostly folks with real problems, like those in these threads, but who have unwittingly entered into a predatory industry that relies on providing overly specific data to people with nonspecific problems.
> but who have unwittingly entered into a predatory industry
How exactly is it predatory? Rheumatology, which rarely engages in "cures" and whose "treatments" are often an exchange of one set of problems for another (if at all), and yet never fails to collect on its patients, might well fall under that umbrella.