Optimism is w orshipped in this country. Indeed, there may be a genetic bias towards optimism in our country because we are mostly descendents of immigrants, whom we would expect to be mostly optimists. I know from experience that those of us who are more realistic are often criticized harshly. People often cite statistices showing that optimists are happier and healthier. But the definitions of "ooptimism" in these studies is not that of the general public. The optimists in the studies do not assume that all is and will be well. They believe that they can cope when things do not turn out will, and that they can influence (not necessarily determine) their lives. In fact, in long-term studies, people who were described as cheerful when they were children turned out to have a lower life expectancy.
Now, I'm not saying we don't need optimistic people. We need a variety of different kinds of people to fulfill various functions in society. Which is my point.
An example of a situation where optimism was a drawback are the people who choose to stay in areas which are predicted to be hit hard by hurricanes, when they had the means to escape. They are sure it won't be that bad. In the case of Katrina, they were wrong.