There are significant problems to that strategy though (see prior video);
1) A crippled/failed nation is a nation with very little wealth, even for the fabulously "wealthy". A borderline impoverished American has more "wealth" than a "wealthy" North Korean. Basically, Un's decadence is about on par with somebody who eats out every night and routinely shops at a liquor store. (with a prostitute addiction.) Conceivably, a middle class american could get most of that ticket, and still keep the lights on. Comparatively, ruling a nation the way Un does just results in the ruler living very low class as well. There are better ways to live such a life without dragging thousands of people through the dirt and starving them to death.
2) With the above in mind, there are additional costs to sustaining a despotic regime, such as psychological/happiness costs. Sure, you get to be the guy who is "In charge", but you also have to watch out for knives in the back around every corner, suspect every wall of having ears, and castrate your own economy to stay "In charge." Does the happiness boost of being "In charge" give sufficient value to offeset all the negatives and sources of systemic unhappiness that come along with this method of maintaining it? (Read the original story about the sword of damoclese, and how the flatterer begged the tyrant-king to take him off the throne in the end.)
Instead, NK could have pulled in with China, and been strong economic partners with their big red neighbor. They could have a rising standard of living, and be a real global contender. Instead, the Kim-Jongs have systematically ground their nation into the ground, and now need "the ultimate weapon" to be taken seriously. They are a pathetic mockery.