To *be* bat-shit crazy, or to *appear* bat-shit crazy? Appearing insane can be an excellent military strategy, especially if you're in an extremely week tactical position such as North Korea is in. It makes your enemies extremely hesitant to provoke you because you may quite possibly engage in a completely disproportional and/or unexpected response. Of course keeping up the appearance requires that you do occasionally actually engage in insane behavior, but a sane commander using such tactics will be extremely canny in employing such behavior only when a studied analysis of the enemy suggests that he can get away with it with minimal real costs. The fact that North Korea is not only still standing, but has managed to repeatedly milk the western world for lucrative concessions despite the apparent insanity of its leaders, strongly suggests that that is the case.
Of course the beauty of such a strategy is that your enemy can never be completely sure exactly how much is an act, and must moderate their own behavior in the face of that uncertainty. Would North Korea launch an all-out attack on our regional allies in response to some moderate provocation, knowing full well that they would be completely obliterated in response? Certainly not. Probably. We hope.