Extremely consumeristic.

Buying stuff is perceived as being successful.

Anecdotical, but designer brands know that Koreans are some of their most loyal customers. The more expensive, the better.

So many fancy cars, here, too. Even in neighborhoods where people live in crappy houses.

If they spend less on stuff, they will spend more on traveling, kids, etc.

There are so many reasons to spend your money, and people don't feel free to decide for themselves that there are other ways to live and spend money. The ingrained sense of community and the fear of going against what is considered normal make that many people just believe one has to buy the fancy water gun when going to the waterpark, one has to go to the Swiss Alps for traveling rather than cheaper nearby France, one has to eat expensive Korean beef rather than import Australian or American beef, etc.

Things are changing, but it takes time and some brave people who are ready to be ostracized for being different than the norm, at the risk of ending up taking their own life.