I'm thinking about a musician blogger I used to read a lot of. He made the point that, unless you're writing music, unless you're playing and selling the music you wrote, you're not in the music business.
He would play covers in clubs. He wasn't in the music business, he was in the hospitality business.
I used to play guitar in church. I wasn't in the music business, I was in the religion business.
Can you find a fun place in the (not-music) business? Probably. Can you get it to a place where it subsidizes your growing gear-acquisition problem? Probably. (I'm a guitarist; over time, you will develop Gear Acquisition Syndrome, or GAS, and purchase gear you don't need. It will happen.) Can you make a living off of it, to where it's your only source of income? Enjoy learning all the Top-40 and playing weddings and corporate gigs. This is thing people do.
As for the Music Industry, well...
The Golden Age of session players was the 1960s. Remember that the only Byrd playing on the first Byrds album was Roger McGuinn, because he had been a session player as a banjoist in the Folk era. There was a decade where Hal Blaine played on every Grammy-winning Top Song. If you were in demand, you were getting Beverly Hills money and working 10-hour days, but if you weren't considered ready for the studio, you weren't getting in. Many bandleaders recorded albums without any of their regular touring-band members.
Then came the 70s, and there were more opportunities for band members to show up on the albums, and the opportunities for session guys were drying up. I mean, they were still there; Toto is filled with the top of 70s LA session players. But it was harder to be the first-call player.
And then ProTools. It became easier for a creative person to set up a mic and a laptop in their bedroom and do it all there. There are still studios, and there are still players that get called in. What may have once been a bunch of people at FAME or the Record Plant could be sitting in someone's living room and plugging your board into their laptop. (Look for Buddy Miller's Rig Rundown on YouTube if you don't believe me.)
I think Tim Pierce has said he moved from being an occasional-session road player to being session-only with Goo Goo Doll's "Name", which was a few years in. But those road years were with Rick Springfield (and on his albums). It's knowing people, and having those people know what you can bring, is the key.
Take me, for example. At church, I met Greg, who is a singer, songwriter and guitar player in the Roots Rock style. He got some studio time and I went in to play on two of his songs. I loved it. It was a blast. I got no money from it. Because COVID, he hasn't played out much, and I haven't at all. There's have to be more recording here than I know about, I'd have to network with those people (and know where they are) and let them know what I can bring, and those people would have to get their music really big in order for me to reasonably switch from being a computer programmer.
And then there's the fact that many of the bigger genres don't use guitars.
But guitar's still a big part of Country, if that's your interest. It's key in Metal. There are definitely guitarists who have popped up later. Joe Satriani was pushing 40 when "Summer Song" came out. Greg Leisz was 40 when I started hearing his great playing on albums.
And, Rick Beato recently did a video about his time as a producer, showing a hard drive full of albums from a number of artists who spend years of their lives in practice rooms making tremendous music that nobody besides them ever heard and ever will hear.
I want to encourage you to learn music, to play music, to love music. But regardless of age, relying on music to make a living is a hard thing.