Spungle, I think that most people think that the world will carry on because it has always carried on. Of course that isn't a proof that it will; after all there were no black swans until they were found in Australia. But it's not a bad rule of thumb. If humans had lived on the premise that the world is about to end, they wouldn't have bothered to survive, but survive they did. Whatever the doom-mongers may say, the mass of humanity behaves as if there will be a tomorrow and in so believing they make that tomorrow come about. Of course, God or an asteroid or a Satan or an alien species might suddenly appear and snuff us out, but healthy people don't live with that as a real fear.