Responses
I think in the comments earlier it was explained that there was some SA involved in addition to all you mentioned. Sorry, cannot rememenber if it is possible to add it as a spoiler, they gave more details in those comments.
I kinda understand Soo Han a bit too. His inferiority complex and his results coming out as an omega what better defense mechanism than to be mean and just be awfully an asshole? I don't justify Soo Han attempting to kill a child twice but depression and other mental illness can make one lose all their rationality. It's like you know it's wrong but you still want to do it because you can't control how crazy your mind goes.