beta
What I read from previous spoilers
Soohan wanted to KMS because he got SA-d that time by the cousin (who's coming to take over his position at the company now) and it was kinda indirectly the kids fault because he wouldn't have been in that cousin's radar if the kid wasn't so clingy to him. It's also partly his jealously and inferiority complex like "this kid is living the life while I suffer so much" that he kinda tried to strangle the kid.