That's a mistake I think that a lot of Western observers make is to assume that Korean nationalism is hundreds if not thousands of years old. When in fact nationalism is incompatible with Korean Confucian tradition.
Confucianism is all about tempering your instincts with intellectual discipline, with book learning.
If South Korea is going to survive, and keep the peace on the peninsula, its citizens need to start conveying support for their state.
North Korea not only wants unification, it absolutely has to have unification. That's really the only way this state can feel secure.
Even North Korean people who are not necessarily happy with economic policies are still loyal to the state itself. It's a military-first state, so whether it does very well on the economic front or not, is not central to public support for it.