Growing up my neighbor down the street was accidentally bitten by a Great White shark, while body boarding, at Stinson Beach. He suffered pretty severe injuries with hundreds of stitches to put his torn flesh back into place. Skipping foreward...today he is a Great White shark proponent.
When I started surfing on the California coast it was always in the back of my mind that an accidental bite could happen to me. Most of the surfers I talked to about sharks thought about them too, but the fear was not enough to keep them out of the water.
With the internets power to provide information I studied the heck out of Great Whites and peoples encounters/incidents with them. Shark bites are not common at all along the California coast. The actual deaths of humans is even lower. Most of the shark bites do serious damage to the victim, but they live. Somewhere around 96% of the attacks are on the surface, with the highest percentage being people located in the surf zone.
Since we are talking about scuba diving where we are not on the surface much, and not in a surf zone, that means our odds of being bitten are even less. Every once in a while someone will see a Great White either from a boat or underwater. The shark casually passes by, like they do more then we will ever know.
It is OK to fear sharks, but we should fear drunk drivers much more.