Small sample size, but of the 2 startup CEOs I know well, it's 2 for 2. There are others who seem fine, but I don't know them well enough to judge their true character.

If we start with a Beta(2, 2) prior on the percentage of CEOs who are insufferable, egotistical fucks, we get a Beta(4, 2) posterior. So the 95% confidence interval on the percentage who are insufferable, egotistical fucks is [28.4%, 94.7%].