The Myth of the Optimism Bias?

Are humans natural, irrational optimists? According to many psychologists, humans show a fundamental optimism bias, a tendency to underestimate our chances of suffering negative events. It's said that when thinking about harmful events, such as contracting cancer, most people believe that their risk is lower than that of 'the average person'. So, on average, people rate themselves as safer than the average. Moreover, people are also said to show biased belief updating. Faced with evidence that the risk of a negative outcome is higher than they believed, people don't increase their personal risk estimates properly.