Wars have always been fought for the profit of the very few and brought about anguish and sufferings for the very many. They have always been caused by the rapaciousness of the leaders. The people have always been the ones who had to bear the grim consequences of the selfish greed and lust for power of these very few who see plunder and destruction of lives and happiness of the many as their self-evident birthright. Wars have had many different stated reasons over the centuries, but the common denominator has always been greed. It's frightening to realize that in every generation there are a number of unfeeling human beings who gladly sacrifice anything of real value in their lives in order to gain power and accumulate wealth. The price does not count, only the booty that is carried home. These emotionally handicapped people do not know of the sufferings of others. They are blind and deaf to anything that might intrude on their predatory instincts and get in the way of their own self-interests.
Wars of conquest of yesteryear
Throughout past history wars used to leave the conquering nations exhausted and impoverished. The greatly reduced numbers of the conquering armies dragged their sore feet and their tired and frozen bodies back to their homes. Back to their countries that were suffering from hunger and general neglect due to the absence of the men who had died or who came back sick and wounded. Only the generals and the nobility lived high on the hog after the conquests and the people had to pay all the rigors, the suffering and the deaths. Rewards for the mighty were of course substantial from the conquered regions, but the poor got nothing but starvation and bleeding.
Today, the nature of wars has changed in some respects. The thousands if not millions of dead and severely wounded are now mainly to be found in the invaded countries where lives are of no consequence to the invading nation. Nothing fundamental has changed however. It's still the people who have to suffer from exhaustion and from the loss of limbs and health. The rulers of the world remain in safe havens just waiting for the booty to come home.