Because when I first played that quarter fed arcade machine as a kid I knew I wanted to learn how it worked. So I spent the rest of my life obsessed with computers. I'm still a hobbyist, I will most likely always be. I'm a programmer though. My reason for game development are the same as listed above, but for web dev too:
Software development (no matter what it is) can be the ultimate creative playground when it is designed to your own specs and built by you. There is no other feeling in the world that comes close. We are the few and powerful who can create "something" out of "nothing"
C2 is the first game engine to "dumb it down" enough for me to actually be productive. Most of my past projects have been swallowed up by things like futzing with screen scaling, reading through APIs, design patterns that turn out to be anti patterns, etc. C2 is like this great big state machine with the API reference and layout editor all built in.