N. Korea is desperately poor, but to keep the population happy with the leadership, political posturing is a major tool of the regieme there. KJI and his co-horts thumb there nose at America, knowing nothing will ever happen as they are basically a small ripple in the world pond.
The US are quite happy to let them goad all they want, it means very little, as China next door have far more to lose by N. Korea becoming involved in any conflict, winnable or not.
China will be the ones who eventually tell it's communist ally to pipe down and behave, but will have to provide fiscal aid to them to do it. N. korea avoids starvation for another decade or so and the process begins yet again,,,