I'm Korean and have an interest in Korean history. My broad view is that it's hard to intervene in Korea from either of the major powers (USA or China). Korea has a long history of being under the rule of someone else, whether the Ming or Qing dynasties who tended to be more hands off in administering Korea, or under Imperial Japan. Russia coming to border Korea in the 19th century also put a lot of pressure on the Korean monarchy, and later in the Cold War, the USSR had it's own influence on the peninsula during the Korean War.
Now North and South Korea, although their existences came out of this sort of competition between the Great Powers, now get to be independent states with their own rulers. North Korea may rely a lot on international aid, but North Korea is still an independent state. It's hard for anyone to intervene without creating a major international incident. If the USA intervenes, then that could provoke a war with China, and vice versa. North Korean leadership rationally knows that they are small and surrounded by people who are not fond of their corrupt government, so they have to grandstand and play both sides off of each other. Pursuing nuclear weapons as a deterrent is their best bet to maintaining their regime, even if it is odious to outsiders.
I have a lot of sorrow for a divided Korea. It would be great to see the nation together and for people in North Korea to be lifted out of poverty, but even in South Korea, things are not all rosy. South Korea too was essentially a dictatorship when it first formed, with an election having only one major candidate after the other one was assassinated. South Korean government still has its problems today, and although it has become fairly rich and modernized, I do not envy their harsh education system or job market, though I say this as a somewhat lazy American too, (Laugh). Realistically, it is just very difficult to see a peaceful solution to the North Korean problem outside of some sort of force majeure
. It seems more likely that Taiwan will become a flashpoint for conflict between China and the USA that will spill over into a conflict over Korea, and Koreans may become devastated once again by competition between the Great Powers.