From talking to other First Class passengers, most are upgrades like us! The others are corporate where the penny pinching has not set in.
Believe it or not speakers are a large part of FC. The deal is that as part of the speaking fee they get a First Class ticket.
I would think most of those folks when they do fly for personal reasons get upgraded either by points, coupons or comped by status!
Incidentally this was not a scientific survey.