The riots in the UK were a shock, it's the sort of behaviour one expects in American inner city ghettos or anywhere with people used to express their passions full bore, not like the stolid British. And, yes, of course there are opportunist baddies, thieves and thugs who know they can murder or pull of a tricky robbery and probably get away with it in the chaos.
But frustration with a life which seems hopeless, jobless, and which sets you in a society where you will receive no respect, and therefore you end up with little self respect, that can become anger-making. And anger and frustration, with nowhere to go, end up exploding.
When our Western societies have turned Capitalism into a religion, turned money into a god, and urge us all to consume more products with built in obsolescence, and buy, buy, buy, but ignore the other side, creating jobs, something will give eventually.
When films, TV and advertising all glorify possessions and obtaining them, and when films are made with heroes and heroines who are mass murderers, thieves or people who take what they want, we aren't exactly sending out 'good' messages.