Most cops are heroes that devote their life (and sometimes lose their life) to protecting the rest of us. They are a wall between you and me, and danger. My grandfather was a Detroit cop during the race riots, and he’s one of my biggest heroes.
That said, I think one of the benchmarks in growing up is the day we realize that authority figures (parents, teachers, cops…) don’t always get it right, and aren’t always good. Sometimes they don’t act as they should, or in a way that is just. Sometimes cops beat people up way more than the pursuit of justice demands. Sometimes, they are out for personal vengeance or agenda, not public justice.
If you brandish a gun at a cop, you’ll very likely die for it, and that’s just the way it is. However, would Rodney King have been right to defend himself? Were the gay patrons of the Stonewall bar right to defend themselves? I think so. Cops are people, just like you and me, and we all have our triggers, our prejudices, and our occasional feet of clay. The difference is that the cops can back it up with their bigger sticks.