On the other hand, civilisations do rise and fall. My country, Britain, has been much more influential in the past than it is today. We get used to situations quite quickly, and then it seems they have lasted for every and will always last forever: but they never do.

And contrariwise, sometimes the doomsayers are identifying a real threat, and the reason it doesn't come to pass is because people addressed it and averted it, which might not have happened without the fore-warning.

Just because you've been OK up until now doesn't mean you should be complacent about the future.