I can see how people would willingly throw themselves into the chaos but only if there are a sufficient number of other people also causing destruction. So how would a single fight (oh say a bar fight) gather enough combatants that it reaches that threshold of violence?
Note: This is not related to riots that were "pre-planned".
It's like the ultra-violent version of "Six Degrees of Kevin Bacon". A and B get into a fight, C and D jump in on either side to help out their buddy, and before you know it, angry mobs with torches and pitchforks are rampaging up and down the street, protesting dogs and cats living together.
It is never that simple there are factors and issues that are all piled upon each other and the right thing happens at the right time. Like say in town that is politically divided and there is a lot of tension. Say the two of the big names in the issue get into a fight it can quickly escalate to a full scale riot.
Alternately, if someone writes a story about the fight and posts it online, and the public sympathy is on one side of it, and the basher is a cop, you can do exactly the same thing. Just ask a certain old Egyptian in a Red Sea resort...
The Rodney King case in Los Angeles is one example of how this could happen, albeit the "fight" was one-sided and the riot only happened months later after the accused police officers were all acquitted.
The recent deadly riots in Urumqi, China had a fight start in Guangdong province which led to hundreds of deaths in Urumqi which is on the other side of China. All you need to do is identify with one of the parties.
Basically, a Uyghur accused two Han of raping some Uyghur woman and claimed the police did nothing (because of racism). In the ensuing fight the Uyghur was killed. Some blogger then posted the story and claimed the Han not only got away with the rape but also the murder, which incited massive anti-Han riots in Urumqi. Eventually, the original two Han were executed for murder, the Uyghur blogger who posted the story got something like 10-15 years for inciting violence and then a few (to a dozen) of the rioters in Urumqi were given death for murder (which is likely to just cause more unrest). Around two hundred people died, mostly on the first day of rioting when angry Uyghurs went after the Han neighbourhoods in the area.
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