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.

Hindsight bias makes surprises vanish.

Lucky risk takers use hindsight to reinforce their feeling that their gut is very wise. Hindsight also reinforces others' trust in that individual's gut.

Survival prospects are poor for an animal that is not suspicious of novelty.

The evidence is unequivocal, there's a great deal more luck than skill in people getting very rich.

Finally, the illusions of validity and skill are supported by a powerful professional culture. We know that people can maintain an unshakeable faith in any proposition, however absurd, when they are sustained by a community of like-minded believers. Given the professional culture of the financial community, it is not surprising that large numbers of individuals in that world believe themselves to be among the chosen few who can do what they believe others cannot.

If you care about being thought credible and intelligent, do not use complex language where simpler language will do.