In destructive economic systems, there is a feedback loop wherein it becomes self-confirming that greed and aggression lead to gains rather than acts that involve "playing by the rules", sharing profits, cooperating and helping others to prosper. As activities on Wall Street and in transnational corporations confirm, successful players are expected to produce income by any means possible, pay workers as little as required, charge as much as can be obtained for products and always tap into new markets for an enlarged customer base. It, also, requires a perception to be created that some newly devised product is desirable and must replace the older versions for which there is often built-in obsolescence.
Moreover, new stocks of resources, the raw materials from which products are made, must be tapped for global industries regardless of whether the people in the regions supplying these stores want to share them or not. In a similar vein, large scale commercial operations heavily rely on fossil fuels in the obtainment of raw resources, haulage of them to manufacturing sites, production of finished products and transportation of merchandise to market. So a steady source of petroleum must, also, be guaranteed.
This entire process, therefore, requires government leaders in support of their countries' industries to wrestle control of needed goods. Simultaneously, they have to convince the public that there are solid reasons to carry out assaults in resource rich regions of the world -- places like the Caspian Sea, with its oil estimates ranging up to about 200 billion barrels or 15% of total world reserves. Add to this treasure the fact that the Caspian Sea, also, is believed to contain 4% of the world's proven reserves of gas according to the Congressional Research Service, an organization supplying bipartisan information to Congress, in its report titled "Caspian Oil and Gas: Production and Prospects".
markets. Iran has enlarged its tanker terminal at Neka on the Caspian Sea coast, enhancing its capacity to deliver Caspian oil to refineries for local consumption, with an equivalent amount of Iranian oil exported through Persian Gulf terminals." 
Put alternately, uncooperative countries, such as Iran and Venezuela, with assets coveted by western corporations give the perfect excuse to western governments to demonize them, threaten them and seek out destabilization of their regimes. All the same, the maligned nations will not let their reserves be plundered whether bullied or not by outside groups willing to use any means possible to obtain their prizes.
Further, full government support of corporate goals is nearly always available. After all, members of Congress want huge donations for reelection campaigns.
At the same time, it becomes quickly clear about whose interests they, ultimately, serve (rather than the public's) when government officials' desire for these contributions, lucrative future jobs after exiting public service and maximization of personal profits from their financial holdings are added into the mix. Indeed, "members of Congress invested nearly 196 million dollars of their own money in business that receive hundreds of millions of dollars a day from Pentagon".  So taken all together, these conditions provide plenty of motivation to keep the nation's war drums beating.
Therefore, wars are big business, most notably for investors and employees in the aerospace and defense industries. The related purposes, like the ones guiding most corporations, are hardly humanistic. Instead new sources of revenue, cheap resources from conquered lands, and new markets for products and services are the sine qua non.
Accordingly, the Pentagon and the corporations that supply goods and manpower for wars have one general intention in mind and that is not even to win wars. Winning wars would mean that money-spinning contracts and growth of the organizations' national and global influence would shrink. Jobs, then, would disappear, high salaries would not be commanded and gargantuan earnings would cut back if wars were, actually, won and, thus, completed.