In 1913, a young Franklin D. Roosevelt wrote in a private letter that a war among the major European powers would be so deadly and destructive that it could not be imagined. In 1914, he learned differently.
There are so many historic examples of war being so unlikely, so terrible in its prospect that it just "could not" happen. And yet it did.
That is why, in the large sweep of history, people who want to see peace should never underestimate the potential for war. Even those, like the mistaken Roosevelt, who feel rising prosperity is an antidote to conflict.