He sounds like someone who would give a great talk. I can see that happening for sure. I've devoted my life to a lot less before realizing there was more out there. These people put so much time into their work there's little left for a broad life - unless you make some clear boundaries like Mark is doing now. Maybe this will be a one time thing and, as you suggest, he may regret not making more time for other areas of his life. Maybe he'll manage to carve out more time for himself.

His book "Get Smarter" is a pretty amusing read, too.