What opportunities are you missing by overrating risks? I am almost certain you are not socially courageous enough. Hanson always goes on about missed opportunities from FDA being too strict.
Maybe, more than “overrating risks”, that's another instance of the ethical injunctions for which people wouldn't push a fat man off a bridge to save five people chained on a railway.
As everyone here knows, it would be a stupid idea to switch from airplanes to cars out of safety/terrorism concerns: Cars are a much more risky means of transportation than airplanes. But what other major risks are there that many people systematically undervalue or are not even consciously aware of?
The same can be asked for chances.