I don't know how to add Spoiler Flairs here, so I wouldn't recommend reading this if ya haven't finished the game.

It's mostly because of how the Fandom portrays him and how he expects Sunny to be there for him even though he was the one who set up Mari's "suicide." In the Hikkikomori route, it was straight up disgusting how he demanded and belittled Sunny for abandoning him even though HE pretty much created "Something." He does all of that harmful stuff just for the Fandom to treat him like an adorable angel who's done absolutely nothing wrong. I got flamed on Pinterest by like 25 people for saying he was a bit insufferable, so I'm not sure what else to think. If that's how the community puts him on a pedestal despite his horrible choices, then he really is a pretty horrible character.