It's like the survival of fittest. Only the ones who can take the abuse (and keep quiet about it), the grueling hours, the near-zero salary and the lack of prolonged sustenance without falling victim to drugs and alcohol to numb the pain, emerge to become solo superstars. The others either end up addicts, or drop out to return to normal life, or find a wealthy man to marry/be his mistress, or in some sad cases, turn to suicide. Some lucky ones remain in the business but achieve only moderate fame. The shelf life of majority of K-pop singers, especially those in girl bands, is very, very short and tenuous.
Damn, success really comes at a high price. In every single industry, it's like you have to trade your life and soul to be successful... fuck I feel like I'm a slave to my studies (I slept something like 25 hrs all last week, ha) but it all seems like nothing compared to what these girls go through.
Essentially, if you want to be successful, and you're starting from the bottom (no family money, connections backing you), you have to live and breathe your work/art. No time for family, relaxing, personal life, anything else. It's harsh. No wonder so many people choose the life of mediocrity... it's kind of depressing, really