Being a professional musician is a bit of a blessing in disguise because it can be very difficult at times. But to think that people pay me for something that I would do anyway keeps me perpetually grateful and privately very centered and more fulfilled. Maybe I'd work in the music industry but in a non-performing capacity. I would say talk to people with experience and ask them detailed questions about their lives. It's very similar to an athlete moving from the college game to the pros.
Many pros have long, respectable careers.
Not many have careers on the level of a Tiger Woods or a Michael Jordan. Do what your heart desires but don't constantly worry about if you should change lines of work. Do what you love but don't be afraid to make it marketable. It sounds like a hippie clich , but be happy in your work. The study of the human experience through literature is very interesting to me.