This is from the introduction to Andy Ngo's recent book UNMASKED. I've substituted hyperlinks for his footnotes, and added hyperlinks of my own. Rioting happens when people who might riot sense a "moral holiday" caused by police failure, and people around them getting away with rioting because the police refused to use "ruthless coercion."

One of the first things you notice in a riot situation is broken windows. Breaking windows starts riots.

Given that the Capitol Hill protests turned violent after someone started breaking windows, it's worth asking if this was done by Antifa provocateurs embedded with the pro-Trump protesters.

As violence continued for the fourth day in Minneapolis and began to spread to dozens of other American cities, I was immediately drawn to images of mysterious masked vandals dressed in black breaking windows. In the grand scheme of mass riots, broken windows seem minor, but as noted by the Minneapolis Police affidavit, the act set off a “chain reaction” that led to looting and arson. Think of it as James Wilson and George Kelling’s “broken windows theory” in a different context. Antifa know the effect that smashed windows, breached businesses, and fires have on crowd mentality. Each act serves as blood in the water. It can turn protesters into rioters. That’s why antifa teach this in their literature that is disseminated widely online and in real life.

In the extreme anarchist literature think tank known as “CrimethInc,” one of their most popular manuals is “Why We Break Windows: The Effectiveness of Political Vandalism.” The booklet, available free to print as an online PDF file, argues breaking windows is an act of protest against capitalism, white supremacy, and the police, and should be actively practiced:

To smash a shop window is to contest all the boundaries that cut through this society: black and white, rich and poor, included and excluded. Most of us have become inured to all this segregation, taking such inequalities for granted as a fact of life. Breaking windows is a way to break this silence, to challenge the absurd notion that the social construct of property rights is more important than the needs of the people around us.

If this sounds familiar, it’s because in 2020 numerous mainstream left-wing commentators began criticizing the very notion of property rights. “Destroying property, which can be replaced, is not violence,” said New York Times reporter Nikole Hannah-Jones in a CBS News interview in June 2020. Hannah-Jones won a Pulitzer Prize for her involvement in the error-laden “1619 Project” in the New York Times Magazine, which argues that America’s true founding is in its enslavement of Africans. BLM cofounder Alicia Garza had earlier stated this sentiment.

“We don’t have time to finger-wag at protesters about property. That can be rebuilt. Target will reopen. The stores will reopen. That’s assured. What is not assured is our safety and real justice,” Garza said in an interview in New Yorker magazine in June 2020.

The word “violence” is being systematically remade to conform to their worldview. Looting and arson aren’t violence, they argue. And yet physical violence directed at their opponents is also not violence but rather “self-defense.”

The CrimethInc manual on breaking windows goes on to explain that taxpaying businesses are fair game to target because that ends up hurting police, who rely on public funding. The intellectualizing of their arguments tries to mask the ruthlessness of their worldview. They don’t care whom they harm, what livelihoods they destroy, as long as it furthers their political agenda.

And if the sociopathy of the booklet wasn’t clear enough, the anonymous author argues that, at the end of the day, window smashing creates work opportunities for laborers who otherwise would be wasting their time doing something else. “Anyone who truly desires to see an end to property destruction should hasten to bring about the end of property itself. Then, at last, the only reason to break windows would be thrill seeking,” the manual states.

By the way, if you think the idea that Antifa acted as provocateurs on Capitol Hill is a "conspiracy theory," let me remind you that for months police blamed the start of the George Floyd riots on one allegedly racist guy who broke windows in Minneapolis [Minneapolis police say 'Umbrella Man' was a white supremacist trying to incite George Floyd rioting, by Libor Jany, Star Tribune, July 28, 2020].