This is just my personal opinion - it's speculative, I can't back it up I'll admit that right away. It's just what I'm seeing.
Yes, there are definitely SOME white people who are infiltrating the BLM protests and wanting them to turn violent because of an agenda. I think SOME of these guys are white supremacists, who want to provoke the crowd to violence to make black people look bad; I also think SOME of them are anarchist types who consciously want to hijack a BLM protest into a more generalized f-the-system down-with-capitalism thing. And as always in protests of this nature there are ununiformed cops who are trying to create an opportunity for their buddies to stomp protesters for "disrespecting" them. But....and this is just me...I don't think all of those people put together make up most of the white infiltrators that are causing damage and looting places.
I think most of them, are just...well, tourists, for lack of a better word. That's who I see when I look at MOST of the videos showing white individuals busting up things while the BLM protesters around them yell at them to stop. These are rich or upper-middle-class white kids who are simply there to engage in what they think is a fun activity. They don't have a political agenda. They're not being paid - they have disposable income and are well capable of buying a plane ticket or buying their own gas and driving to a protest. They may certainly have opinions one way or the other, but they're not really there because they support or oppose BLM. They're there because they saw a protest with a potential for violence on the news and thought "hey, let's go do that". Most of them clearly do their thing without caring whether the crowd around them is agitated or not, as you can see in the videos; those that do try to incite the crowd do so not with the aim of making the protesters look bad - they're not thinking that far ahead - but rather just because it's easier to break windows and tag walls and steal crap and not get caught or feel as guilty when a whole crowd is doing it around you.
Case in point? Jake Paul. You guys all heard by now, I assume, that during a spate of looting at a shopping mall in Scottsdale (or Phoenix, some place in Arizona) after a protest there, Paul took his camera and went and live-streamed running around the mall and hanging out with looters; he even took a liquor bottle. Right now he's getting serious backlash from the YouTuber community for it so he's making all kinds of excuses; but never mind that. Jake Paul is a freaking millionaire. He didn't go to the protests because he's legitimately angry about the treatment of black people; and he didn't go there to loot. Like his brother Logan (you'll remember him from the Japan "suicide forest" incident), Jake Paul has no agenda whatsoever outside of self-aggrandizement, which he converts into YouTube ad money. He went to the protest so that he could say he was there, pushed his way to the "front lines" as it were so that he could say he was pepper-sprayed with the protesters, and then went to the looted mall out of morbid curiosity. He was a tourist. Now okay, not all the white kids going up there to play "protester" for a few hours have YouTube channels, but they're there for the same reasons. "I was at the riot and I busted out a window lol I'm so bad yay me!"
I think your theory sounds about right. I can only speak from my own experiences with much much tamer riots in Europe, of course.
Riots are uncontrollable, that is part of the phenomenon. The initial protest might be organized, and people might try their best to give out guidelines and draw lines; actually even the most radical left usually does that. But there is no way to really control what will happen, and a wide variety of people will take part and do their own thing.
There -are- people who think 'violence against objects' is generally justified when you fight 'the system'. -Some- (in my experience not the majority) of them won't differentiate between small business and big businesses, between social institutions and institutions of the executive or legislative. Some of them don't understand that looting does not equal expropriation. To some of them maximum chaos is the goal, be it to achieve maximum attention, maximum confrontation with the cops, or simply maximum damage to get their point across.
Some of them who are middle or upperclass, especially of the younger generation, simply don't comprehend that they are destroying people's lives. They dream of an alternative society, have the financial means to live a 'bohemian' life, and kind of assume that everybody could do that.
Another big factor is simply - rage. People get out of control when agitated. Especially when they are scared. And rightfully upset. This is why deescalation would be so important. Instead police forces often keep provoking. This is sometimes intended, sometimes a sign of incompetence, often both.
Agents provocateurs always have been a thing, and obviously they are a real danger now. They will do anything to discredit the protests, and some of them won't care if people get hurt or even die.
And yes, last but by far not least there is a rather big group of people who don't join in because of 'the cause' or because they feel solidarity.
There are the marginalized who will take the opportunity to get that iphone or TV they always wanted. There are those whose lives are really so fucked up that they go berserk when they have the opportunity to 'strike back'. There are drunks or drugged people who will do stupid things. And there are a lot of excited, often testosterone driven youth (not exclusively youth though, I have seen fifty-something daddy-types burning random cars) who feel it's an adventure and somehow cool.
From my experience these are not necessarily only rich kids, though. I personally know some of the teenagers who were looting at the G20 riots - they came from various financial backgrounds. They were celebrating an insane day, they didn't really know what it all was about, they just thought it's cool to get a stash of free booze from the liquor store they destroyed (on a positive note: Some of them discussed the incident later and might even have learned from the experience). And for some it was indeed those 15 minutes of fame, they took selfies and uploaded videos in front of burning barricades. The 'riot-hipster' is not photoshopped (and I have to admit, I still find him insanely funny):
As I said, the riots I have seen were tame compared to what is going on in the US now. But there is a lot of frustration and a lot of unarticulated rage simmering in our societies, and in an uncontrollable situation like a riot it will break out. Some people will show their best side and become heroes who protect others, and others will show their worst.
