Maybe recent simulations (link 1, link 2) showing that self-delusion can be an advantage is not surprising. There are empirical studies suggesting overconfidence in one's ability can improve performance. This has been shown for swimmers. Radiolab composed a stimulating podcast on the topic.
Inflated self-confidence is considered a virtue, so long as it doesn't border on arrogance, because it signals a person interested in self-improvement. Because it is a virtue, people are consistently optimistic about the future, telling themselves and others about the person they wish they could be, not the person they are.
Perhaps it relates to what people seek in life. I contend that in addition to striving for wealth and hedonistic happiness, people want their lives to constitute a riveting story. A great (and handsome) man once said...
A poet might say the value of living
is the power of your story.
That a story can bestow the poorest of men
with Earth's greatest glory.
Life would seem so futile,
if story after story would repeat.
Conflict, injustice, with all its harms,
ensures man's story is unique.
To believe one can accomplish the seemingly impossible, and then to actually do it, makes for a grandiose story. Much more grandiose than a story about one who soberly assesses their likelihood of winning, claims they are unlikely to win, and by chance, wins. This over-confidence, you see, ensures the unlikely victory is attributable to self-worth, not chance. Moreover, if those who yearn for this story put forth greater effort, then self-delusion would be correlated with achievement. It's just an idea...
Of course, we must be skeptical of the claim that self-delusion is correlated with achievement. How many studies found the opposite and could find no outlet for publication?
