I think solely it's because of the environment if you grew up in Korea and he ended up like that he actually got out on the better side. They are so fucking harsh for not having parents especially if your an orphan, of course he should apologize but the environment there can really deter you from apologizing.
yeah, adding on to that^ person's point, Korea sucks ass when it comes to students. Bullying cases are so severe that if you want to survive you either learn to just fucking fight until they let you go or become timid and just go with whatever they say. and compared to other comics, here you can see that he struggles to actually not just say sorry but in general talk properly. cuz he isn't even used to talking to people cuz he lives alone and doesn't attend school. yeah he's an asshole but in this case he has much more depth than your avg emo boys
Why is there always an unnecessary violent character that can't even say the word "sorry" and, just because of a sad background, everyone starts pitying him and justifying his actions?!
Like, dude, I don't give a shit if his past was sad. He's an asshole and that's all!
You having a traumatic past don't give you a "be a jerk" free pass! (ノ｀Д´)ノ彡┻━┻