> Just like how World War I was initially called “The Great War”. If you had called it “World War I” from the outset, people would look at you funny, like “Do you know something I don’t?”

This is why I didn't, at the time.

Jokes aside, some people knew and so it was also called (though not very commonly) World War starting 1914 and First World War from 1918. Because of course it wouldn't be the last. World War 3 was first talked about in 1941. And the famous idea that World War 4 would be fought with sticks and stones was first mentioned in 1946.

So the correct answer to "Do you know something I don’t?" is "I know human nature"