Google "deindividuation" to see that once part of the mob, there were probably no "some of them" acting for any other reason than as part of the general violence and theft. I can't prove that there was an absence of people thinking that they could change things by their actions (however dumb that would make them), but then absences are notoriously difficult to prove - can you prove a presence of them?
There's been a lot written about these "riots", as if the authors were looking at individual rioters' motivations, but basic mob psychology suggests that becoming part of a mob relives the individual of individual motivations or at least the usual demotivators that affect their behaviour as shown in (or similar to) the Milgrim and Stanford Prison Experiments. My take on the thing is that there was some initial anger influenced by general and specific circumstances but then, when those involved saw that their actions weren't being clamped down on, they became a mob and lost some of their personal self control, which is when the hell started breaking loose.