Writing is never a “mere” hobby. I suppose in the strict sense, if you’re not earning your living at it, it’s a hobby. But some hobbies are more central to human wellbeing than others, especially if one works with discipline and rigor to produce something that has some value and isn’t just trite or banal or sentimental words. The value may be just for yourself. It may be for ten readers. Or, if the market lottery is kind, it may be for a lot of people. I find a lot of inspiration in Brenda Ueland’s If You Want to Write.