Bullying is a strategy that results from certain psychological incentives and coercive institutions. There is a reason it is highly prevalent in coercive atmospheres (school, prison), but very rare in freely associated atmospheres (business).
If theft is profitable, people will become thieves. Sure, people who come from poor backgrounds might be better at it, but if they weren’t there, other people would become thieves.
If bullying gets power and resources, people will do it. This is why it occurs in schools and prisons, because it works. This is why it doesn’t happen at the grocery store, because it won’t get you power or resources. The benefits of bullying often outweigh the costs in non-freely associated arenas, and the costs usually outweigh the benefits in freely associated arenas.
You aren’t bullied because someone was a jerk to their kid. You were bullied because the culture of education and our culture’s regard for children is rancid and it becomes profitable to bully in those spaces. You were bullied because your teacher is a coward, the schools system doesn’t care about you and your parent is ignorant and not very thoughtful. That bullying kid is just a reaction to the adults’ incompetence and indifference.
At the individual level you can stop bullying by making the costs of bullying you higher than any benefit. However, to end bullying more generally, you have to change the cultural incentives.