You don't understand. We're talking about nuclear warfare. My country would be blown up anyway. The best course of action is to avoid more destruction. The only reason for me to bomb someone else even though I'm sure to be destroyed would be for revenge, which is stupid and results in millions of further deaths.Are you joking? Does that seriously work better in your eyes? Letting your country be bombed, and just throwing your hands up in the air over it. I can't even imagine. Lets hope you never run a country, because your citizenry would be sitting ducks.
MAD may be the only thing that keeps people from blowing each other up, but despite what most people think, it is not a Nash equilibrium, where the best idea is to not fire nukes as long as no one else does. The thing that seperates it from being a Nash equilibrium is the fact that the more nukes launched, the more death, so in the perspective of the entire human race, the best course of action is to never fire a nuke, no matter what other people do. So that's what I'd do.