Riots
For starters, let’s characterize accurately what is going in certain cities these days. What is occurring are riots.
Riots are a form of protest, but to call riots “protests” is to lump together those who are peaceably demonstrating and those who are engaging in violence against property (and people who would try to stop them from rioting).
Riots are undoubtedly as old as civilization. They occur when some segment of society is suffering severe injustice with no hope that in the normal course of things those injustices will be addressed.
It is all but universally the case that when we look back on riots that occurred long ago we see how understandable they were. Yet, we can rest assured that at the time those participating in the riots were roundly condemned for their actions.
Many people want to characterize rioters as people who are using some event as an excuse to do what they always want to do — destroy property and take things they want without having to pay for them. I have no doubt that such people exist.
If that were all it takes, however, we would be having riots constantly. For riots to occur there have to be people involved who were pushed to such extremes of action by ongoing injustice with no hope of relief from it.