How do you know? Are you a cop? If you are, I may accept your statement - if you have stats to support it. I have family in law enforcement, other family who were cops but no longer are, and I worked as a civilian supporting the police department for a couple decades. Another thing, I said "some". What part of "some" do you not understand? I did not say "all". My buddy and later roommate during high school was a punk, getting into trouble. After high school, he was so used to being around cops that he became one. He was one of those who enjoyed beating perps. As he matured, he tired of it and no longer wanted to be a beat cop, and became a motorcycle officer (and is retired now from SFPD). I remember the stories he used to tell me. I wouldn't call him rogue back then, just full of testosterone. Two of my brother-in-laws became cops, and both later resigned because they didn't like the culture, they were too "nice". So It isn't a 50/50 thing, as I said it's "some". I've been around a lot of cops who aren't in either category.
I'm increasingly seeing buffed, bulked-up cops who clearly appear to be users of anabolic steroids. Perhaps this is contributing to the situation.