It's not just on here, sweetheart. There are plenty of mean people out in the real world too. ファンポップ is no different from the outside world. What, あなた expect everyone to hold hands together and sing Kumbaya while handing out チョコレート to each other? No, the world doesn't function like that. あなた might as well just get used to the fact that mean people exist. あなた can't deny the fact that all of us are mean at some point in our lives.
Because internet, my friend, is a place where people feel limitless to post anything since あなた can't identify them. Don't give a care about those people.
Because some people on social networks are mean because あなた dont know their identity so they think that they can f@uck wits so yeah they are just cowards behind a computer screen.