I do this stuff for me, and I know many other indies that are the same way. Thats the big secret for a lot of developers (small ones at least) - they dont make stuff for their audience, they make stuff for themselves and it just so happens that their taste is relatable.
I make stuff that I never put online, solely for my own pleasure. I enjoy programming, its like a giant puzzle for me. I actually find the process rewarding. Like a clockwork maker who takes pride in his craft.
Coolio has a line in one of his songs that I love because it encapsulates why I do this: "if hip hop didnt pay I'd rap for free."
Oh don't get me wrong, I think I work in a similar way. Every now and then I'll have an idea for a small project and then work on it in my free time, never going public.
Never large projects, more like exercises. Something I could get to a usable state in a few days. A dungeon generator or simple puzzle game or something. Anything doable that I think I'll enjoy and might learn something from.
I think it is much more enjoyable to make something you are interested in, than trying to construct a checklist for some hypothetical market you don't care about.
That feeling of somewhat quickly going from a simple idea in my head to something tangible is great, especially when I'm used to long periods of nothing.