For me, becoming an enthusiast begat building your own computer.
Basically, a few years ago, I had (and still have) a Dell Dimension 530 E4300 1.8GHz Dual Core and I felt it was running a bit slow.
So I decided that I was gonna take £300 and upgrade the hell out of it (keep in mind at this point I knew next to nothing about computers). So after searching a bit I decided that the three aspects of my computer which needed upgrading were CPU, GPU and RAM.
I started with the RAM. I spent £100 on 4GB of OCZ DDR2 and then I took it to my local computer shop and they told me it would be £50 to install the RAM. At this point, I naïvely took their word as gospel, so I brought the PC in and sat there for 15 minutes while they upgraded it. While I was there, I saw that their prices were £60 for a CPU installation, £30 for a GPU installation and I was thinking to myself, its gonna cost me another 50% of what I paid in hardware to get the things to work in my system. After the RAM was installed, I decided to go home and educate myself to see if it was feasible to do it myself in order to avoid these charges.
Little by little, I learnt, mostly through trial and error, about the peculiarities and idiosyncracies of computers.
I tried to throw in a Q6600. Rejected. I assumed it wasn't working and returned it.
I tried to throw in a Q6700. Rejected. I knew that it was something to do with the computer and not the chip then. I finally got privy to the fact that my chipset didn't support quaddies so I finally ended up with an E8600.
As far as GPUs went, I just went with the hype and straight away got an Palit 8800 something or other. Tried to install it. Didn't fit nor did my power supply have the right cables to support it.
Returned the 8800 and settled with a nice XpertVision 8500GT and a new power supply.
Since then, I try to keep up to date with all the tech news and my knowledge has become more profound over the last few years.
I finally did my own build in the summer of 2011 (2600k, XFX 5770 et cetera) but I doubt I would have been able to without all of my previous technological adventures/misadventures.
From wanting to simply make my Dell PC run a bit faster, I guessed I just happened into technology enthusiasm.