I fly economy because I own my own business and I would rather take the 1000 dollars I save on the ticket and spend it on something else.
Spending 100 hr to sit up front in the business section is a waste of money when you can fly a different airline and get a very comfortable seat and meal and not put up with the cramped seating in Cathay.
When I worked for Schlumberger I used to fly First Class out of Nigeria and then around the world every time I had days off. Had to do with the currency exchange rates and my travel allowance.
I can tell you that after the initial novelty wears off First Class is not all that fantastic as well.