Overconfidence is a powerful source of illusions, primarily determined by the quality and coherence of the story that you can construct, not by its validity.

If people are failing, they look inept. If people are succeeding, they look strong and good and competent. That's the 'halo effect.' Your first impression of a thing sets up your subsequent beliefs. If the company looks inept to you, you may assume everything else they do is inept.

People like leaders who look like they are dominant, optimistic, friendly to their friends, and quick on the trigger when it comes to enemies. They like boldness and despise the appearance of timidity and protracted doubt.

Optimistic people play a disproportionate role in shaping our lives. Their decisions make a difference; they are inventors, entrepreneurs, political and military leaders - not average people. They got to where they are by seeking challenges and taking risks.

Facts that challenge basic assumptions-and thereby threaten people's livelihood and self-esteem-are simply not absorbed. The mind does not digest them.

In strategic decisions, I'd be really concerned about overconfidence.

There's a very good reason for why economics developed the way it did, and that is that in many situations, the assumption that people will exploit the opportunities available to them is very plausible, and it simplifies the analysis of how markets will behave.