@Sweet_Seats Actually the only incorrect part of that was including the girl who stepped in as a "bystander". She actually got involved and you turned her away. That was the victims part played well but she was not merely a bystander, she simply could not do anything without effort on the victims side too.
Bullying is perpetuated by bystanders ignoring it. If you allow it you are part of the problem. If they all openly disapproved of the bullying it would be different but they stood by and watched without any real position taken for the most part. This is what he means by the bystanders. Its the people who don't say anything when they see injustice, thus injustice continues.
Successful bullying requires all 4 of those things to continue. They all enable it to happen. If any of them were missing the bullying would not work. He does know he's the final nail in the coffin though, but the whole problem feeds into itself until he breaks. He tried to commit suicide and that didn't work, so now he's going the shooter approach.