It's always been a hobby. I work in a non-tech field, I have just liked it better than alternatives, and like the tinkering bit.
It started about 1993, as a freshman at Bronx Science. The school's internet terminals ran AIX (IBM X Stations with these nice big 21" CRTs). Senior year, a friend gave me a CD from Walnut Creek. That was Slackware. Started playing with it, and liked it. I was using a custom built 486 I bought at a computer show. However, things were far from easy as documentation back then was hard to find.
From there, first year of college (1998), I moved to Red Hat (at 5.1) and with the help of a guy on IRC got the Sound Blaster drivers compiled, X running, and everything else I needed. The college computers at the time ran VAX (not so Unix-y) and Digital's OS/F, so again I felt right at home with a Unix-like OS.
From there it was a wrap. Haven't touched any proprietary system since. In between there's been periods of using BSD, and a lot of "distro hopping."
Twenty three years later, I'm almost back where I started - Fedora. Still a hobbyist, still tinkering.