(Different topic, out of curiosity.) Why bother protesting anything at all?

I mean, we're both smart people. Surely we agree that http://www.youtube.com/watch?v=2aT9p36fgHU#t=3m35s indicates the police can do whatever they want, and nobody really cares except the victim.

And there's really nothing to do about it, or any way to change it. Nobody cares about protests except the protesters.

I wish it weren't that way, but, given that things are that way, then why bother fighting?