Okay, that may be the case, but it's very difficult seeing people around you, people who are of the same demographic as yourself, be consistently killed and imprisoned unfairly without expressing anger through destruction and violence. It's easy for people observing to say "vandalism is wrong, therefore this protest has no validity". It's hard to say "these people are expressing their anger after years of oppression, we need to work together to solve this problem". People don't like to solve problems.
I understand why they're angry and I sympathize but that doesn't make it OK or immune from criticism . You can be angry and voice it, but once you cross that line and resort to violence your're no longer better than those your against.