G. Mark’s Answer
In most facets of my career, I've been presented with compelling opportunities. I originally got a scholarship to a university to study medicine. After being exposed to a lecture about computer science, I was drawn to it. In computers, I ended up working on projects that got me involved building things. And from there, I ended up in computer and electrical engineering. Somehow, I got involved in entertainment as an adjunct to one of my projects, and did that for awhile. So the answer to your question is, "Because it seemed the most exciting and fun at the time." I don't think most people are that lucky, but I can tell you that most scientists and engineers do what they do because they're simply compelled to. Even sitting alone in the bathtub, if they relax for a minute or so, they'll be thinking about their science and engineering most of the time.