I'm not sure that's entirely true. We naturally always try to paint the "enemy" as an unhinged maniac ready to unless destruction on the entire world at a whim, but in reality I don't think this is pretty much ever the case. A population with the industrial and intellectual capability to develop a nuke in the first place is going to have grander ambitions than going out in a blaze of glory. I think even ultra-fundamentalists like the Taliban mostly just want to build up their own little vision of a utopia.

I think a part of the reason North Korea plays crazy is because they have to. If the US didn't think they'd push the big red button, then we'd invade them in a heart-beat. Mutually assured destruction only works when you believe the other guy will push the button. So you need the bomb and then you also need to make sure everybody thinks you're willing to actually use it.

Sorry for the repetition but I'm just going to repeat this every time it comes up. Maybe some day I'll make it a bot.

North Korea has enough conventional rocket artillery within range of Seoul to level the city. This is how Kim was able to run his nuclear program to completion in the first place. It also hasn't changed.