Take me as an example. My Forever Project is Physics. I have a degree in both CS and Physics. I made the decision years ago to work in the industry as a programmer, because it's more fun and pays better than being an academic, especially where I live. I'm not officially involved with my old University, but I still take part in their mailing lists, think about Physics in my free time, I even submit simple papers to journals [+]. I don't have delusions about being a good physicists or ever doing anything of any importance, but Physics still fascinates me, I like to ponder its problems and sometimes marvel at its beauty.

[+] http://arxiv.org/abs/1208.4990

Edit: Btw. you are right in saying that these things are a "distraction in life", but I think it's a good distraction, like a hobby.