My fiance and I are both musicians, and he is big on watching YouTube and commenting to give…

My fiance and I are both musicians, and he is big on watching YouTube and commenting to give constructive criticism to help, but after his comment got featured in a video with a "famous" "producer" video giving him criticism, he is now getting bullied and pulled all his videos down due to the hateful thing people are saying, that's pathetic... Why do people bully someone for having an opinion, the same one you claim you're having, yet when he gives it you turn into a whiny baby about it and go after him/someone for being human and having an opinion. But why would someone of power make it to where other people will do that to someone else, and tear them up, if you didn't want the opinion don't post it. He post his videos and took criticism, but when it turns into bullying because of some big shot telling you to go after someone, you're pathetic, a very sad person. I'm sorry for the rant, but this is bothering me, and now I'm worried for my fiances mental health because some coward in front of a computer screen.