I really need to get back to that mindset. I keep catching myself unconsciously checking my hobbies and abilities for marketability. I've been playing guitar for almost three decades, one of them spent in a touring metal band. When I started, I used to enjoy making music so much that I played and composed so often an album would just come together naturally. And then another one and another one, I just couldn't stop.
These days, I no longer sit down to play just for myself and the moment — instead, I catch myself thinking, “Can I sell sample packs from this? Record a course? Should I code a VST plugin for it and sell that?” And after weeks of moments like this, all I have are three random riffs and frustration.
I try to look at my music as something that I do because I enjoy it. I play in a casual/amateur band and I regularly have to remind the guys that I do it for no other reason than because I enjoy it; I'm not interested in playing gigs. Not everyone sees it the same way.
I know a few musicians that tried to make a living out of music similar to your story. Most have now stopped making music and are both frustrated with the music industry, and angry at listeners for not valuing their work.