I think the people is just more vocal, not that the protest changed its opinion, but now they have an excuse, violence, to go against the cause they did not like.

"Violence" like stoping the traffic. If that is violence...

Stopping traffic can easily kill people if it stops a medical transport, for example.

Even if it just ruins the day for thousands of people, I have zero sympathy for such assholery. Whether you call it "violence" is unimportant.