I mean, you're right. School bullying more often than not functions on a mob mentality. If one person is being ostracized and severely bullied most, if not all, the kids in the class will eventually join in on it to varying degrees if for no other reason than to avoid being the odd one out themselves. Could you really blame the kid being bullied for resenting his entire class in that situation? Even if most of those kids aren't really malicious per se and might even be friends with the bullied kid if the situation were different.