War progresses many industries and humanity as a whole. “War! What is it good for?” by Ian Morrison is a good read.
The fact that it would very often be "cheaper" or more efficient to deal with any individual problem ahead of time somewhat loses it's appeal when you consider the huge amount of potential problems that are costly to even evaluate as to the benefits of dealing with them in advance.
Few people know this, but that was actually the original title for "War and Peace". It was his mistress who insisted that he call it "War and Peace".