Everyone bullied adrien for his mum being dead and his father doesn't care about him, they bully him even more because of that. The only person who doesn't bully him is Marinette she's adrien's best friend, everyone adores marinette they all want to be her friend but she only wants to be adrien's friend. They all are jealous of adrien because of that so that's also another reason why they bully him. A lot of boys have a crush on marinette and the girls want to be like her and adore her