" cost a lot more than $500 billion to raise per capita GDP by ~7 fold."
That's a good point, but remember that North Korea, in spite of being the most backward and poor nation on Earth, is full of Koreans. A strong creative drive and high levels intellectual life and potential talent and a flair for protest and organizing reform will do a lot for a nation. Most nations would be lucky to unify with 15 MM Koreans, no matter how poor. Within a generation of getting freedom, I expect them to be doing well.
Remember that it only took RoK twenty years to go from a brutal dictatorship among the poorest in the world to the 1st world nation it is.
My expectation on the cost being far too low, was taking into account that South Korea is an excellent nation and that they may be better at fixing eg North Korea than a lot of other countries in their situation might.
Most countries in the world would simply not be able to fix North Korea, or pay for it. It would be a perpetual disaster, with the North falling back apart, languishing from quasi-dictatorship to quasi-dictatorship.
The difference between South Korea lifting itself up over 20 or 30 years, and what's going to happen with North Korea, is responsibility and imbalance. South Korea is going to end up assuming immense responsibility for the well-being of the people in the North, rather than the North existing as its own country; and the South will be massively rich by comparison, that imbalance will draw out very large sums of subsidization in the process of bringing the North up to speed to the South's standards --- there was no such scenario with the South when it originally climbed up out of poverty, no stark comparison amongst their own people essentially. It will be viewed as very unacceptable to have the people of North Korea with a per capita GDP of $10,000 after 20 years, while the South perhaps has a $50,000 per capita GDP at that time. Many in the North will not want to stay there in those conditions, and by moving to the South they will generate a significant new financial burden. Either way, it's going to be very expensive.
Obviously working long hours isn't necessarily optimal for productively, but the average Korean certainly works harder than the average human. (And I'd wager this extends to the North too.)
If you look at the post WWII economic performance of South Korea, and North Korea until ~1980 or so when their leadership started to impede them, it is clear the peninsula has what you might call very high levels of latent human capital, seeing as how just about all of their physical capital had been destroyed.
That's a real potential problem, as is the lifetime impairment of childhood malnutrition. But I expect defectors from any regime to be the kind of entrepreneurial misfits that never quite fit in and demand their environment adapt to them.
I hate to disagree with so-called "numbers", but that is simply not very well veiled racism. If you read that Wikipedia page, it mentions prosperous nations that don't fit their "rule", like the wealthy democratic Botswana.
That's a good point, but remember that North Korea, in spite of being the most backward and poor nation on Earth, is full of Koreans. A strong creative drive and high levels intellectual life and potential talent and a flair for protest and organizing reform will do a lot for a nation. Most nations would be lucky to unify with 15 MM Koreans, no matter how poor. Within a generation of getting freedom, I expect them to be doing well.
Remember that it only took RoK twenty years to go from a brutal dictatorship among the poorest in the world to the 1st world nation it is.