Unpredictable and isolate events can have huge impact. humans tends to look for explanation and predictability models. Experts are in some cases the worst in predicting those events.
Human brain makes lots of mistakes due to biases: confirmation bias, necessity to simplify and map events to patterns ignoring casuality, ignoring missing proofs, believing in miracles.
We tend to overrate what we understand and underrate what we don’t understand. In a company projects often fail due to that. When a new technology emerges, we tend to highly overestimate or understimate (Ed: dot com bubble, bitcoin)