"Is it worth swimming in shark-infested waters to surf a 50-foot, career-record wave? Is it riskier to make an action movie or a horror movie? Should sex workers forfeit 50 percent of their income for added security or take a chance and keep the extra money? Most people wouldn't expect an economist to have an answer to these questions--or to other questions of daily life, such as who to date or how early to leave for the airport. But those people...