The last year of high school is insane. Again we invoke the Korean Grading Act. Just to interview at Seoul National University, you probably have to be one of the top two students at any of the top high schools in Korea. The competition to get into a good university is insane. And the major Chabols hire from these universities as does the government and the medical field. Everyone knows the ranking of the university and the ranking of the students within the various university departments.
The last year of High school is when students prep for the Government tests that will determine which university they can apply to. Your life is determined by a test score and not by your dream. Koreans go into majors because those are the only majors available to them. They go to universities because those were the only university available to them.