Wow, hadn't thought about that one in a long time. I thought it was an old Scott Hanselman blog and I was correct! I'll have to reread it, been years now.

I'm not sure there's much why to it exactly. I feel like a small fraction of people I've met in life were truly passionate and excited about the work they did. Most had some passion for an art, or a hobby, or for their kids very commonly, but people who really want to grow and master their craft are somewhat rare generally. Most folks just want to do well enough to keep their jobs and then go home to whatever they actually care about.