For our Everest expedition, the previous few years had offered a better than average weather pattern during the month of May, which is when most expeditions plan to reach the summit. The guides became complacent and assumed that May of 1996 would hold the same good weather pattern. They should have made their decisions based on overall weather probability.
A more typical weather pattern settled in during May of 1996, causing the guides to be caught off guard. This resulted in some of the members of the expedition freezing to death on the trip down from the summit. After the first Gulf War, Americans believed that fighting in the desert offered quick victory. Our recency bias made us assume that the second Gulf War and the war in Afghanistan would be just as easy.
We now know differently. Business owners sometimes have a string of good fortune that is based on pure dumb luck. They believe the string will continue and go “all in”, even though the laws of probability would suggest a more cautious approach.
