While the chaebols represent a huge part of the South Korean's GDP, they account for only a small part of the jobs in the country. Whether leaving them for another job is easy, that I don't know. Depending on the country's culture, leaving could also be very bad for future prospects.

Samsung has 0.1 million employees in SK out of a population of 52 million. It’s big, but that also makes it more difficult for them to replace people who quit.