The way you said you "cannot stand this man" felt so personal and diplomatic all the way, it made me laugh. Anyway yeah, there was character development. People are now used to see only this character being a monster level jackass, that's why it feels very awkward to them and makes them think there is no development ongoing
Oh no i wasn't trying to point out to you "where others are coming from" as to why they don't see character development or excuse them. I was honestly trying to see their way before actually commenting on the fact that yes, there has been, like you said, i meant to said you were right. I say it because it's simply an objective thing. Character development is character development, doesn't really matter if this is deep classical novel level of character development or daryl dixon level of character development. That's why i understood you completely when you said people where odd for not admitting said development, because you are right. The "i lost" scene shows it perfectly. What always pushed Jk's life all this time was winning, that's the only scheme and reason of being admitted in his life, so in this case people fail to understand that "losing" to someone else is literally his overall being and everything of his up until now ceasing to be. Mind you Jk ain't my favorite mangago dude either but in this case i simply gotta be 100% realistic just like you

i’m not here to defend jaekyung at all (i hate the guy), but i think people saying he’s had no character development in this chapter is a little odd. and no, my point isn’t going to be him realizing his feelings for kim dan.
i think the easiest way to tell that his character has BEGAN to develop in this chapter is his admit of defeat. kim dan has him beat. before jaekyung could and would never admit defeat, but in this chapter, he admits defeat.
i don’t mean to rant, and i absolutely do not like jaekyung (like i cannot stand this man. i can’t even reread most of this story bc of how much i hate him), but i can’t let that hate blind me from his development, despite how small it is. hopefully it he just keeps going up from here, because let’s face it, kim dan and jaekyung are going to end up together anyway, so he might as well be a good person when that happens