Have you ever heard of a music artist who was extremely dedicated to being successful in music for decades, but it just never worked out?

The vast majority of people who try to make it in sport or any of the arts and not successful in the sense of being "famous" or making a lot of money.

The thing is of course that its unlikely that people will have "heard" of an artist that has no success as they are going to be unknown.

In my case I know of one person who I played in a couple of bands with in the 1970s who has continued to perform live, compose, record and publish music but has had no financial or commercial success at all. I would certainly call him dedicated.

Of course. Every city has dozens of bands and solo artists who perform regularly, sometimes for free, for decades but have never had a recording contract, not even a local one. Some of these are really quite good.

Music is like the other arts: there's a lot more first-rate work than there is a market for it. It's compounded by second-rate work getting public attention it doesn't deserve because someone's got a rich backer, connections, or a famous name.

This is one of the most common tails out there, especially since the advent of the internet, there are millions and millions of people out there that write music and try and make it big. And yeah a lot of them actually are good. Even if you're really good, and your songs are great, there is no guarantee you'll "make it", in fact the odds are very slim. Like you're asking, people do this their whole lives sometimes and don't get much further than their hometown. Most musicians like this have jobs, or are just poor. But you also got to remember, there are lots of different jobs and different levels of success. A lot of people make a great living just being a studio musician playing for other people. You can be in a band for someone like Eminem (meaning he has a back up band, none of whom are famous). There are some bands that tour nationally but aren't well known. I'm not going to discourage you from your dream if that's it, always go for it, I'm just saying, have a backup plan. But to answer your question, the vast majority of musicians don't make a living on it as their sole means of living.

they may not be "marketable"