korean society in general has very high expectations of their people. the entertainment industry used to be far worse than it is now but there are still things that go on behind the scenes, like encouraging eating disorders, idols' self doubt, money troubles since the way that kpop groups are designed you barely get paid unless you make it BIG, unfair contracts, long training and rehearsal hours as well as long schedules. on top of this, the pressure to never make any mistakes because the public can turn on you so quickly: for some minor drug use, a scandal, a mean comment or just looking tired/upset at a music show - people will write negative comments excessively online. Plus a society that dismisses mental health issues.
if u look at some examples.. sulli was always criticised for things such as "weird behaviour" and going braless, she was bullied so much online and she even tried to take legal action which didnt go very far. goo hara died a month after her best friend sulli and battled legal issues and her ex threatening to destroy her career by releasing a sex tape. Jonghyun suffered from depression from a young age and felt the pressure of being in the spotlight was more he could handle. He regularly spoke about his issues and it showed through his songwriting but in the end he decided he couldnt stomach it any longer. Other actors/actresses talk about career and money worries, societal pressures and feeling like a burden on others. Recently moonbin, it's an unconfirmed case but widely suspected to be suicide - he spoke often about his health issues, doubts and feelings of inadequacy, mental health etc. and he was obviously overworked. The korean entertainment industry is really only for those who can manage to push through all these awful things...