“Simplifying” things is valuable when it gets rid of extraneous complications that obscure the fundamental truth. But when it removes the fundamental truth, it should be avoided. IMO, describing non-career interest in music as “just for fun” actually obscures all of the things that are interesting about the relationship humans have had with music in our written and unwritten history. Some people play music because they feel it brings them closer to God. Some people play music because it is therapy. Some people play music because it is a way to “listen to music with their hands.” Some people play music because they can’t not play music. Some people play music just for fun, and if they didn’t do that for a hobby, they’d put ships in bottles, it's not that meaningful to them. Lumping all those things together obscures the very thing that is interesting about the question “Why do you play music.” If we want to simplify things, we should throw away the distinction between career and non-career. It’s actually not that important, most people who want a career in music like playing music for its own sake, and also want a career. Separating them from those who don’t want a career in the industry doesn’t tell us much.