Who is the happiest guy to be an F1 driver?

[Scott]

My vote after watching the driver press conference (and watching him in past interviews) is certainly Romain Grossjean. 

Why are so many drivers so glum doing a job most of us would die to have?  Even when I'm having a crappy day, I can always pull out a smile for the hotel guests...why can't these guys do it for the cameras?   

Another note - Vettel is possibly the rudest, joking around and talking with the guys next to him while the guys in the back row are trying to answer questions from the reporters.