Lankov discussed this in an 2009 interview:
The North Korean government is afraid that if they begin reforms, the result will not be economic growth, a Chinese-style economic miracle, but rather Eastern German or Romanian collapse followed by reunification. And they are afraid that in a unified Korea they will find no place for themselves.
But these people’s major goal is not economic growth. When someone asks, “What is the strategic goal of North Korea’s leaders?” I usually answer, “Their major strategic goal is to die in their beds.” They want to stay alive, they want to keep the regime going, and they don’t care much about economic growth because they believe that economic growth will take them to prison. And they are probably correct. So maybe, sooner or later, someone will try reform. But I would not expect it to happen anytime soon.
Q: We occasionally hear from defectors that there are reformminded officials in the middle levels of the government and Party who realize that the whole system—political, economic, and everything else—has failed. Can these people, who have enough information to know how bad things are, have any influence over the long term?
A: In the long term, maybe, yes. But we shouldn’t forget that once these mid-level people become high-ranking people—and this is a necessary precondition for them to have any influence—they acquire a vested interest in keeping the system going. Because if the system collapses, its leadership will be in trouble, and they know it. This is partially because their rule has been exceptionally brutal and, at the same time, economically very inefficient. So the major problem of the North Korean elite—maybe most of them, and probably Kim Jong Il himself—is that they understand very well that the system is not delivering, but they simply don’t know what to do about it. They don’t see any way out. They don’t have any exit option, and honestly I don’t know what can be done about this.
http://www.rfa.org/english/commentaries/lankov-nk-02202009171534.html
Their strategic goal of the Party Elite is for the Party Elite to live like royalty. Part of it is the lifestyle (which is much higher than the common people) but a big part of it is the power. There are some people who just get a hard-on over the idea of having power over people, to make them beg for favors.