North Korea not crazy, but incredibly intelligent and calculating. It's rather foolish and dangerous to think otherwise.
As the old saying goes, you're not crazy if everyone is actually out to get you.
Consider a world where they followed a similar path to countries like China and Vietnam. Their people would be a lot better off, they’d have a much stronger military, and they’d be able to be much more of an equal partner with their allies.
It's the same with the development of nuclear weapons. There is a near-zero probability that North Korea will engage in a first strike with nuclear weapons, but a very rational way of self-preservation.
The North Korean regime is reprehensible but their actions are rational, from a self-preservation perspective.