The actions of a riot might be that entities within areas gets destroyed, but that's hardly the goal.
It's similar to when kids mindlessly destroy public properties in the night in smaller cities. It's not because they just like to smash stuff, but because there is nothing else to do. Rioting tends to be the last possible action you have in your pocket, until a civil war appears. When people are feeling that no one is listening to them, they try to find other ways of getting heard.
And as history has shown us time and time again, riots sometimes work. I wish people didn't have to resolve to violence, but as an outsider who been watching the police brutality in the US for as long as I can remember, it doesn't surprise me that people has had enough.