The best book I ever read on this topic was "
Making Money Making Music: No Matter Where You Live" by James Dearing. It completely changed my attitude about music and most importantly, my attitude about myself as a professional working musician.
I was lucky enough to read it when it first came out in 1982. I was able to put his methods to work right away and i can honestly tell you that in the three and a half decades since, I've made a ton more money and had a lot more fun than I would have otherwise. It's immeasurable to me. Like a switch in my head that flicked on somewhere in there that's marked "before" and "after."
Take this thread topic. What are we actually saying? Dissatisfaction. Either with the music, other musicians, lack of opportunities and more than anything else: dissatisfaction with ourselves for not being rich, famous and groped by adoring throngs in adorable thongs (if you catch my drift).
Briefly, it's a means of evaluating your skills and marketing them. In other words, creating the gigs you want, as a business. At the time I read the book, I actually believed that was exactly the opposite of what I wanted to do. That I'd be "selling out" somehow, and I had too many doubts about my own abilities to even consider (the downside of hiding in the bass section of orchestras too long, I think).
He guided me through it, and somewhere in there I felt a sense of freedom and exhilaration at being able to answer "yes" to one particular question (you'll know it when you see it, believe me) that has never faltered in the slightest. I've never done any work since, because I PLAY bass.
The reason I'm being purposely vague about his methods is because A: you might not want to read it (or follow the internet troll tradition of arguing about it anyway) and B: because your mileage will vary. Count on it. Before I read the book I thought the opportunities were bleak and confined to genres, but ever since I've been aware of the staggering number of outlets for musical expression, with the only bounds being those we put on ourselves.