During war time, our economy shoots up because of all the jobs being made producing wartime goods and actually getting involved in the war. A long time war could lessen the population and advance us technologically, many technological advances came during wartime and for wartime. "But they are dying!" So? People die all the time and at least these people will be benefiting the earth. If we stick to a no weapons of mass destruction then it's all good.
Peace, allowing countries to co-operate instead of wasting their few resources to kill each other. War slaughters innocent populations and uses up limited resources. Resources that can be used to advance humanity in the field of Science and Space exploration. We can get the most out of our resources if we work together.