I wonder what that fifth of my brain would have been thinking about for the past 10 years, if not programming. Maybe it would have been dancing, or painting, or soccer. Instead of context switching into thinking like a computer, it'd be how to move my body around or how to meld colors together. I feel like that would lead to a much more fulfilling life.
I used to program for fun in middle school. It was probably halfway through high school when I stopped programming for fun. It was always that little nagging voice in the back of my head: Play it safe. Programming is an in-demand field! You're good at it! Look at all of that awesome shit you made.
At this point, the only "hobby" I have is programming. I don't even know what else I like anymore.