Its really more complex than that;
The whole NK issue is all about promises made after the Korean Conflict - The UN , SK , US, Japan and China all have made promises to NK from everything to economic to food and industry relief <- now however NK has to meet certain conditions to get these promised relief packages (money) which they did meet some and failed on many <- they did get some relief but certainly far far from what was promised.

NK says that they did their fair share - and that the West owes them big time ?
The West and everyone else say that NK does not even come close to meeting their share ? ?

Bottom line;
North Korea feels that they have been (F--cked) over long enough by these false promises.