Responses
With the way it was laid out, it is inevitable that he would worsen. They could have talked to him instead of fearing him and leaving him alone in the house. They could have taken action instead of hesitating because Jaeha selfishly holds unto his desire to not let Yoseob get treatment. Yoseob would have been fine then.
So I agree with you. He would have been fine, but instead, he wasn't. Because he was left behind. He had no use anymore, got left behind, and thus he became worse and caused those people to fear him instead of helping him.

Why is it that the scarred ones always gets the shortest end of the straw in a story? Why do they end up as always the villain, the murderer, the monster? Why do they not have any happy ending even if it's just living not behind bars or not in a hospital???
Yoseob just needed someone to understand him, someone who would help him. He didn't need much, he just needed someone to hug him to keep the monster away. He just needed someone to tell him he's ok. He's already fighting against it in his own way, all he needs is a little warmth that would hold his hand when he falls down...
But sure... let's just give him to the hospital. Let's give him to the strangers who will help him and give him medication. Let's forget family.
He's scary, after all. He makes everyone uneasy because he's different and seemed like not right. And he's become worse than before.
Nobody asked why he became worse?
Poor Jaeha, poor Taeho...
T^T I'm fricking crying! Why didn't Yoseob get a little assurance that he was ok, that he'll be fine, before he broke? Lots of chapters bout those two having a pity party and Yoseob's small parts only showed him being alone and getting worse?
Oh poor Jaeha... poor him, he needs someone to tell him that it's ok. That he can make friends. Yehey! Taeho's helping him, and now he became confident and has solved most of his problems. His only problem now is that unusual brother. Let's just get him far away. He's not needed anymore anyways. Jaeha already has friends anyways.
I cried reading that. Yoseob asking if he's not needed anymore. Because I knew that's what was going to happen once Jaeha got the confidence to stand up on his own.
It's always the 'crazy' ones that gets left behind. T^T