It's not just an assumption, they are open about it. It's not a coincidence that kpop idol are forbidden from dating (they enforce it very strongly btw) and that they organize events were fans can pay in exchange to sit down with them and hold their hand for a few minutes.
Their business model has always been that they prefer to charge a single super fan 900$ for a limited edition album than sell a 10$ albums to 90 people.