maybe ur feeling compassion towards the "abandoned/neglected" child in him, but he isnt the good guy. especially if he (and it looks like he did) didnt only want to get rid of but tried to and almost succeeded in getting rid of his younger brother - all because he was jealous of him. not saying that i hate him cause he was a child and the feeling that ur over looked cause ur not good enough especially if the eldest is a blow in many ways, and he dealt with the situation as a child would (by trying to make the "problem" go away). even get why he hates his brother now that he's an adult, cause nothing has changed. but i would blame the parents not my younger brother. so yeah ur opinions is unpopular for a reason.
I agree.
I already know that I'm going to be the one person with the unpopular opinion here, but as much as the story's narrative is telling me that I should be rooting for Youngjoon, I find myself preferring Sungyeon more.