We have these unwritten rules about how much change we should have to face and how fast it can come. But really nature doesn't share these rules. We know this by periods of great upheaval and cataclysmic events such as massive earthquakes, Tsunami's and volcano's. Even rouge waves can come in the middle of calm ocean waters. We see it in many human events as well such as economic disasters like the depression and even World Wars.
I am continually amazed with the generation that witnessed both World War I and World War II. There should have been a rule against two such events happening to the same generation. Can you imagine a wife having her husband march off to war never to return and then watching her son march off to the second world war never to return?
Even though we know change can happen on a massive and even destructive scale, we almost refuse to believe it could ever happen to us that way. So, the mind protects us from what it considers to be destructive thoughts with just a simple mechanism called denial. This is proof that our mind is not a very accurate thinking machine. This pre-programmed "belief bias" can actually completely filter out vital and very useful data that would help us recognize change sooner and be better prepared to adapt.
So, the next time you are certain about the future or the outcome of a project, stop a minute and beware of your "belief bias" before proceeding.