Because complaining makes the situation SO MUCH BETTER.

I had this conversation (or some version of it) on more than one occassion in the desert:

Other Guy: Man, I can't stand it here.
Me: It's not that bad.
OG: Whatever. This place totally sucks.
Me: Isn't this your first deployment?
OG: Yeah, but it still sucks.
Me: Be glad you're not in the Army. They're here for 18 months.
OG: Yeah, well, they signed up for it.
Me: In much the same way you signed up for the Air Force, right?
OG: You don't understand, man. You're not married.
Me: Oh, so because I'm single, my relationships don't mean as much?
OG: (blink...blink)