Why do people hate Ross? I genuinely want to know what exactly did he do to make some hate him so passionately.

Because he was insecure in relationships? We know it only happened after Carol cheated on him. There's a whole discussion about this between him and Rachel for God's sakes. Hey and Chandler was super paranoid too with Kathy and Monica too in the beginning. But no one says anything about Chandler. Joey was a playboy who landed DOUL also because he slept with the casting lady. He could never keep it in his pants and never even called the girls later. While Ross was always loving and serious in relationships. He's an amazing father, son and brother. So what really is the problem here?