Enjoyed reading the article & the comments.
One thing I'd add -- being a "working musician" really is a grueling hand-to-mouth existence for most of its practitioners. Springsteen (like other famous acts) being one exception, since he seems to have been in good shape financially since the 1980s.
For instance, I just read a new interview with the influential LA punk band X who describe their life in the 1980s as being in a "working band" -- some if not all of them weren't college graduates, they just fell into a situation where by touring, they could make just enough money to justify not taking up a different line of work. Tour, earn enough money to take some months "off" to write new songs, record, tour, repeat. When they finally stopped, Excene Cervenka said in the interview, it was partly because they were pushing 40 and at least she (and maybe some of the other members) felt their life was just too financially insecure. Add to that the fact that most working musicians don't have good health insurance or any kind of retirement provision.
Yeah, it's a life that's totally different from manual labor -- but it's by no means a comfortable middle-class life for most musicians.