"If everyone thought that way, it would be a lot simpler," Ghost says with a slight sigh. "7.8 billion... Assuming we're talking about Earth, that's the twenty-teens or early twenties, right?"

It's tangential, just a bit of context before he moves on. (There's enough information in the folder that Senku will be able to put together that Ghost's world had a very different kind of apocalypse, circa 2035.) "I wish you all the luck I've got. It's too late for at least that many, for me."