Like many others here, my Dad bought me my first "real" knife -- a Schrade 3-blade Old Timer stockman. I whittled with it for a few days, sliced myself a time or two, and probably within the first month I broke the tip off the clip point. I thought it looked ugly and didn't want to carry it anymore. It would be years before I started to appreciate knives in any serious way.
In 2003, I started working as a chainman for a survey company. I bought all the gear I thought I'd need for the job, and dug right in, training with a few different crews until I got the hang of things. One of the crews I worked with had a guy who was really big on knives. He had a Kershaw Leek and a Spyderco Delica, and for whatever reason, they immediately struck a chord with me. I knew I had to have a good knife for myself. Not long after, I went with my wife to the mall to see what was on offer at the knife shop. Somehow, I allowed myself to be talked out of a Spyderco and into a CRKT M16, tanto blade. For what I was doing, it was a stupid choice, and the guy totally fleeced me on the price, but I was green and it looked "cool".
I decided I needed more knives, went online and found BladeForums, and a few other forums of its ilk. That did it for me. I've been buying and carrying knives ever since. Not a day goes by that I don't carry or use at least one knife, and there's pretty much never a time that I don't have one within reach. Interestingly enough, the guy who got me hooked on them to begin with turned out to be what we would all consider a casual knife enthusiast; he knows what brands are good, but his interest ends there. I ended up surpassing him in pretty much every facet of the hobby and eventually began to teach him a few things about them!