For some individuals peace is a bad idea on certain levels. War cannot exist without it, just as life cannot exist without death. However, for other people, the idea of "true" peace connotes concord in international relations or possibly properly handled societal strife. so people still prefer war continuously than peace due to benefits in war and disadvantages of peace. peace can have a diadvantage for some individuals and because of that they will continue to enjoy conflict and not peace.
Conflict has existed for a very long time between those who believe that war is always and everywhere an evil that can and should be abolished and others who believe that war is unavoidable and in certain situations essential, righteous, and preferable to a "unjust" peace. From a religious standpoint, there is conflict between those who believe that people is inherently "fallen" and always prone to giving in to the temptations of greed, fear, and xenophobia.