I'm confident that a lot of people in those threads are genuinely obsessed, but I feel like most are incredibly self-aware and embrace it 'ironically' - for want of a better term. The superficiality, the vapidity, the commercialism of it all is a fun escape from reality. It is a universe that doesn't really exist - amplified by the fact that Korea is so culturally and physically separate to the West. Western music and culture is so obsessed with 'integrity'. Is the artist a true representation of the character they portray in their medium? If not, then forget them - I feel cheated.
K-pop turns plastic into gold.
This doesn't necessarily justify anything, the threads or tastes, but it's my explanation.