I am fairly certain I'd love the job. My only concern would be whether, after a while, the romance of flying would become jaded and I'd wish to become landlocked. But for the privilege of thwarting terrorists plus flying all the time, sign me up.
That's exactly where you're wrong. The chances that you'll ever come face to face with a terrorist are next to nil, and the result is that the novelty will wear off within weeks. Boredom is already taking its toll on the current bunch of addicts who signed up to be marshals after watching too many 'Die Hard' movies. They think they'll be waltzing in like John Wayne to save the day and instead they're having to pretend to be just another passenger.
At the end of the day you're just another low-paid, bored-riged security guard, without even the freedom to walk around the thing you're guarding. No glory, no kudos, not much fun. Count me definitely out.