Dan Olweus, the father of studying bullying and anti-bullying interventions, also studied this. He found that fighting sports did not help bullying at all, and there was even evidence it made it worse.
It's not so surprising when you think about it. Bullying is about power, but it isn't being good in a fight itself that makes some kids have power over others. It's social, not physical. The victim had the ability to strike back physically all along, they don't need special training. In theory the victim could stab the bully in the back in plenty of ways - even literally. The reason they don't do that, and the reason the bullies don't fear it, is because all the ways the victim could strike back would be scorched earth. It makes no difference if it's with freshly learned BJJ or a weapon.
It's not so surprising when you think about it. Bullying is about power, but it isn't being good in a fight itself that makes some kids have power over others. It's social, not physical. The victim had the ability to strike back physically all along, they don't need special training. In theory the victim could stab the bully in the back in plenty of ways - even literally. The reason they don't do that, and the reason the bullies don't fear it, is because all the ways the victim could strike back would be scorched earth. It makes no difference if it's with freshly learned BJJ or a weapon.