It may sound crazy to say, but the truth of the matter is that there are some groups of people who benefit from violence (and who, as such, have an interest in promoting wars, in order to keep on enjoying their benefits).
The first group of people who benefit from violence is that of weapon manufacturers.
The second group of people who benefit from violence is that private security contractors, who often provide the mercenaries necessary to fight various wars.
The third group of people who benefit from violence is that of the contractors who are often given the contracts to undertake ‘reconstruction’ once wars are brought to an end (and new ones started, to keep the gravy train going).
The fourth group of people who benefit from violence is that of (certain) humanitarian aid agency contractors: who, for instance, get contracts to transport aid to war zones at very lucrative rates.
There are nice books you can buy to understand the economics of violence (and the economic angle in terror, so that you can see the bigger picture, as events unfold in the world). Some of these are books you can buy online, and pay for them using, say, a card obtained at walmartmoneycard.com (from where you can also access the WalMart money card login page). You can also pay for most of such books using PayPal or even check in some online bookshops.