When people are compared with others there will be disputes. If there are those that brag about their well-being there will be disputes. When there is a group that wants to remain at the top they must do things that will cause disputes. Many poor people can be happy living the way they are if it wasn't for media and it's projection of others that are better off. As long as there's an elite there will be people attempting either emulate or dismantle the elite. An enemy nation may be talked through but with the elites wanting something from the enemy nation or trying to save face and reputation the enemy nation will continue to be an enemy nation because of all these things the elite wants from this conflict.
As long as there is scarcity of any sort of goods, or services or other commodities, there will be people who are willing to take what they need from others by force. Discontentment in general, and desperation drive people to crimes, but this is not because of an elite, it's because there are always those who want to get ahead at another's expense. Even if everyone had equal means there would still be someone willing to attack you to take your share.
The main cause of violence is selfishness, the origin of war, is in selfishness, as is the case with class disparity, oppression, etc, and selfishness affects men and women of every class.