I wrote a post arguing that what is irrational overconfidence for an individual can be good for society. (In short, scientific knowledge is a public good, individual motivations to produce it is likely too low from a group perspective, and overconfidence increases individual motivation so it's good.)

To extend this a bit, if society pays people to produce scientific knowledge (in money and/or status), then overconfident people would be willing to accept a lower "salary" and outcompete more rational individuals for the available positions, so we should expect that most science is produced by overconfident people. (This also applies to any other attribute that increases motivation to work on scientific problems, like intellectual curiosity.) As a corollary, people who produce science about rationality (e.g., decision theorists) are probably more overconfident than average, people who work at MIRI are probably more overconfident than average, etc.