Yeah, also it shows the comment is ignorant of history.
In the immediate aftermath of the Korean war, the North was actually more prosperous than the South. That changed with time, dramatically so, but initially it'd be reasonable to see the north as having better economic prospects.
Considering that north and south korea share the same "culture", wouldn't they be an example against your assertion?
Isn't the bigger impact that one is sanctioned by the world's sole superpower and the other is not?