I took my first steps away form proprietary software, with open source
Ubuntu, back in highschool. I was just looking for a new experience then.
It was like trying to ride my bike further from home than I had been before,
or exploring a part of town that I hadn't been to before. Nothing
ideological. I don't think I knew what free software was at the time. I
don't even think I cared very much that Ubuntu/etc were open source and not
free.
I learned about Richard Stallman and his views, slowly, over the years.
Mostly through his articles, articles about him, web forums, and YouTube (the
last one is a little blasphemous, I know -- sorry). The more I learned, the
more I supported Mr. Stallman.
Then, late last year, my laptop broke. I did a lot of research about free
software and laptops since January. I bought a free-software compatible
laptop last month; I use Trisquel with it. It's the first time I've used a
fully free OS as my primary (and only) OS.