Responses
He simply wasn't raised properly and has no sense of morals. He got where he got thanks to his own effort and endurance so he got used of doing things his way. It's not about WHY he did that, it's about HOW he'll learn to care about other people i.e Dan, which is something he's never experienced before. Well except for the gym granny which translates to his compassion towards Dan's granny. That's about it.
It makes sense why Jaekyung turn out to be a freaking a$$hole but so? Nothing in these 3 (that's way too many) chapters justified or tells WHY he chooses(because it was a choice) to be such a d!ck to Dan.
I suggest y'all re read but if you don't want to:
1. Uses Dan's financial situation to manipulate him
2. Exposes Dan to a stranger while having s3x because he was "jealous"
3. Had s3x with Dan after he was badly injured and it caused his rear to tear.
4. Accuse Dan of trying to sabotage his match without having any proof
and that's half of it, he has no redeeming qualities whatsoever and I'm not saying this just because, I want to see what Mingwa is going to do because it's a hard one and it takes a good writer to know how to make the audience believe their deserve to be together. If after this Dan's warms up to him then this is not worth it anymore.