Fun and the challenge are the main reasons for me but also the fact that I would not like to lose the amazing privelages that come with your licence, whatever one you have.
Up here in Scotland we have so many islands that are only a short hop accross the water but may have a very restricted ferry service, non existant on Sundays which makes flight a far better option and quite often cheaper due to the geography and distance you would have to drive in order to catch that elusive ferry.
A lot of my friends fly because they couldn`t be ar**d having to do it all again if they let it slip.......
I guess that once its in the blood not even the most enthusiastic blood tranfusion could remove it.