Sure, this is one of those gee-whiz studies that lets us make fun of some professional groups: Psychopaths make the best investment decisions. But let's not overlook the grain of truth in the findings: For some decisions by some people in some circumstances, it is necessary to turn off, or at least override, emotions. Think not just of high-risk investors but also of soldiers and rescuers. We judge the advisability of the actions either by the risk-potential reward ratio or by their success or failure.