We know a lot about the conditions under which groups work well and work poorly. It’s really clear that groups are superior to individuals in recognizing an answer as correct when it comes up. But when everybody in a group is susceptible to similar biases, groups are inferior to individuals, because groups tend to be more extreme than individuals. One of the major biases in risky decision making is optimism. Optimism is a source of high-risk thinking. Groups tend to be quite optimistic. Furthermore, doubts are suppressed by groups […] But remember that the internal incentives that shape how the group perceives risks and rewards may be very different from the reality of the risks and rewards in the external marketplace. Those incentives can distort risk perception.