Back in 2011, I lived in London, and there were riots.
It all started with peaceful protests against an instance of police brutality. Then it grew as more people joined and both sides escalated. Then it spread throughout London as people with nothing better to do got involved as they saw that they could loot and smash stuff without punishment
It was reported internationally at the time like some sort of noble class warfare. The have nots rising up to protest inequality. It wasn't.
We'd just try to live our lives as normal, except everyday we'd walk past the same groups of local kids that, instead of sitting in a circle and laughing amongst themselves, would be sitting in a circle with a bit of loot and planning their next smash & grab
The problem with a lot of protests is that they start off well, with justifable grievances, and inevitably other groups of people join in and it takes a life of its own. I'm guessing something similar is happening in the US. If you look at some of the flags that are being waved about, it appears that a lot of bandwagoners have hitched onto this one