I don't think it's helpful to put them all in the same bucket. There's some fundamental differences between North Korea and any others. The imagined history of North Korea is built upon the central idea of an evil enemy out to get them, and their glorious leader - a descendent of divine ancestors - is the only one that can save them. Given the American occupation of South Korea is less than a century old, it makes sense for them to take on the role of the cartoonish villain.
While imaginary evil villains have been a pivotal part of most conflicts and become almost a feature of national identity, with the other example now being the Russians and the Americans, there is no other country in the world that places that story as one of the pillars of their society. Then you throw in the divine nature of the struggle and it becomes pretty clear that this is a very different kind of conflict.
Kim Jong-un needs to fight this war to keep alive the very story that binds the country together, however weakly that is, and allows this regime to continue. The fact that America are the ideal villain to take on that role and that the current president encourages conflict and responds to threats with bullying only exacerbates that issue.
@2cents posted a good article about it
here.