It kind of is. I call it the bullying chain, where one person bullies another, then that person becomes a huge friend and starts bullying more people then those people bully others, etc.
Just because it happens doesn't mean that it's something that should happen.
I was bullied a lot as a kid, was there any point during that time or afterwards where I decided that I'd become a bully as well?
The answer is no, because I had the strength of character to not become a complete jackass