[s3nnyy]

Yet, South Korea ranks high for a First-World-Country in "increase in happiness".

If one sorts "World Happiness Report" according to "change in happiness 2005-2007", the top countries are mostly from the second- or third-world with the exception of South Korea.

[aetherson]

I think that the parsimonious explanation for that is that Korea's wealth per capita has exploded in the late 20th and early 21st Century.