It is sad to see an understandable protest turn belligerent. The July 25, 2012 Los Angeles Times notes that while some folks showed up to protest a police shooting, others came with fireworks, and set dumpsters on fires and brawled.  (Read more)  Mass gatherings are never mono-motivational—people come for different reasons. (See Edward C. Banfield’s “Rioting Mainly for Fun and Profit” here.)