Started my fascination when my dad bought his first laptop way back when Windows 98 was out. That developed into more of a love for the mathematical sciences (physics in particular, which I was previously majoring in in college, now switched to computer science). My real interest in computers started back in my freshman year of high school when I got my first computer I could call my own (PIII, 382MB RAM, 32MB nVidia card, ran stock Ubuntu on that baby).
I started with very, very, very basic CLI commands (Ex: cd, ls, ./run commands, apt-get upgrade / update / install, etc)
Which ultimately has landed me my current job -- 90% of my current computer experience comes from that first computer I had. I took that thing apart, rebuilt it, installed multiple OSes, network cards, you name it. Configured wireless, samba shares, etc.
In fact, I still have that old thing. Still runs, too
From then on, I've always had an install of Ubuntu on one of my computers
As for my joining of Tech Forums... My friend and I were on an old forum named Tech On Vent in which a few members from this site were active. Once that site shut down, I went here because I knew a few people and I was already familiar with the site. TBH I wouldn't have joined if it wasn't for him.
If I remember correctly the reason I joined Tech On vent was because I was wanting to install Linux on my PSP.. which I did
Then I bricked the thing.