And not everybody gets a big bucks job -- many entry level and lower skilled jobs are not far removed from sweatshop labor, and involve work schedules that preclude being able to perform.
Notable in Gioia's History of Jazz is that quite a few musicians were mentioned as having day jobs. But while they got good enough to be recognized for their proficiency, the move that got them into the history book always involved quitting that job.
In my own case, I've never been recorded, except a few demo's that I've done as a favor for friends. I've turned down offers to tour with bands that already had decent album sales. My day job affords me those luxuries. But I also haven't developed any musical ideas that would be missed.
It would be very interesting to see a survey of how many actual dedicated musicians succeed, but I'm already pretty sure it's less than 10%, and for those who work day jobs, I'm pretty sure the percentage is even less. I work in IT, and every single job I get is like walking away further from any hope of music success. I took the past year off IT work (very fortunate to have been able to do that) just to work on my music, but even now, getting my music to people's ears on the Internet is a massive hump to overcome, and it costs a lot of money.
Artists like Prince and The Weekend have backstories of being literally homeless before being discovered. These days, especially during the pandemic, the idea of homelessness is far more deadly, and those guys and many more from the past would likely never even succeed, which is very grim.
The monopolistic route to success being through gatekeepers and big industry is really even more toxic and harmful to our future than ever, but in reality it may be the only possible way to become a full time musician. I'm happy making music that I like, but it's not a hobby for me, it takes significant effort, expense, and time to make and promote it... So when I work my also very demanding day job to pay bills (which also takes significant time, effort, certifications etc...) there is no reasonable way to fit in social media, studio time, networking with musicians, interviews, touring etc.
Citing all that, I can't simultaneously work a modern day job and physically, or even in essence, also be a professional musician with all the modern hurdles of maintaining another entirely different career.
Well, yeah, sure...but it shouldn't be that way. Labels have been the gatekeepers for well over half a century and have barely budged in terms of their dominance. It's largely like every other entrenched industry in the country: they're literally too big to fail. Any "innovation" is either sued out of existence or bought out.
This might be true, but it only happens because those musicians put all their financial eggs into the music basket. If you have some kind of simple "big bucks" income like engineering, that basically removes the need to do unsavory things in order to make music.