Why not when we invented nuclear weapons and set civilization on the path of destruction? Or when we invented fertilizer and set the wilderness on the path of destruction or when we started applying science and set traditional stabilizing religious cultures on the path of destruction? I know why. It's because you're overwhelmed with your own contemporary culture which has indoctrinated you to believe that particular doomsday prophecy. Other cultures have/had different ones and that will surely continue into the future.