There are a lot of poor South Koreans but there are lots with money to burn.
So restaurants, shops and other businesses cater to these people who need something to do to pass time and can pay ridiculous amounts for snacks, drinks, and such.
Used to spend a lot of money, but it was usually entertaining for business and on business trips.
I got one more free flight to Europe or North America using airline mileage. Trying to use it all up before I die. Almost done.
After the war, land in Korea was 'dirt' cheap. Now, that land is very valuable, a source of tax revenue and the like.
All that inflated wealth is sometimes interpreted as inflation. Imagine if the US Fed was in charge of Korea during those inflationary years.
Ridiculous real estate prices and exploding stock market?