FYI, there have been riots and looting throughout most of history, and not just in the US. I'm going to link a list of riots that go back to the early 18th Century. I know there were some that happened earlier. The people who rioted were black, white, the police, the Irish, etc. etc. It was always the result of one group of people who believed they were being oppressed or treated unfairly. So, what did anyone expect this time. I pretty much expected that if this movement grew very large, eventually there would be riots and looting. It's what humans do. Sometimes it's effective and sometimes it's not, but I doubt it will ever change.
https://en.wikipedia.org/wiki/List_of_incidents_of_civil_unrest_in_the_United_States
For tjat matter, could we call The Boston Tea Party a riot, or was that justified because it was a bunch of white people who did it?
So, please take a peek at the list and you will learn a bit of history. Just click on any of the dates and you will learn what caused the riot or looting. I did a little research a few months ago, when the protests started. I learned a lot. I also remember some riots and looting that happened during the anti war protests during the Viet Nam War. I attended a few peaceful protests in New Jersey, but I remember a few in New York City that resulted in riots. This is nothing new. It's unfortunate, but I doubt it will ever end.