>>> he really isn't doing anything material other than having a good time, and perhaps deluding himself as to how well he is impacting his life span.

I would add a third motivation to the list that was best articulated by Ernest Becker:

“For man, maximum excitement is the confrontation of death and the skillful defiance of it by watching others fed to it as he survives transfixed with rapture.”

I highly recommend the work of Ernest Becker to anyone interested in this topic. It is amazing how well the theory of Generative Death Anxiety explains human behavior.

http://en.wikipedia.org/wiki/The_Denial_of_Death