An important consideration is to examine the causes of violence. Violence is just a symptom; anyone is capable of being driven to violence under the right circumstances.
If you have a pit full of hungry dogs and you throw in a piece of meat, then you're going to see those dogs fighting over that piece of meat. But those same dogs could be warm, gentle, wonderful companions if they're well treated and sufficiently fed.
Humans aren't that much different. We live in a dog-eat-dog society where people struggle to keep up with the Joneses and live by a philosophy of "he who dies with the most toys wins." We accept classism and the obscene disparities between rich and poor in this world, so if we're going to accept and embrace concepts like that, no one has any room to complain about the acceptance of violence. If there are people who insist on keeping other people deprived, homeless, unemployed/underemployed, maltreated, oppressed, or otherwise treated like utter crap, then one can expect violence to be a consequence. It might even be considered a moral obligation to be violent if the situation calls for it.
As Jefferson put it, "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."