This is basically a PhD thesis that has been published as a book. It's a really dry, boring read, made up of empirical stats and commetaries on those stats.
Basically the PhD students are positing the thesis that playing music as a CAREER, is basically a path to mental illness and despair, unless of course you are Elton John, Radiohead, Roger Water or Ted Nugent.
In a wider context, the ultra-competitve, and 'only the BEST and most GIFTRED and CHOSEN' rise to the top nature of the music industry has now completed permeated modern capitalism via the 'Gig industry' ie: you only get paid per gig, and only then, based on how many punters you can pull to your gig.
Despite the 'democratisation' or the 'music industry', I wouldn't call it that, more like a mafia-style cabal with NO unionisation, steady wages and definitely ZERO health care, being a muso only aides the rich and chosen.
Personally as an 80-90s 'indie kid' we KNEW the music industry was BULLSHIT and a SCAM, and followed a DIY ethic via the american hardcore and C86 groups. Kid's follow that model, don't be a careerist wanker, make your music and fuck the rest, success will find you.
The book took me so long to read as it's basically a thesis and I would read it at bedtime as a sleeping aide.
Anyway the book is an important document, but your typical muso would prefer to read a Lester Bangs book.