How about the bravado of the startup "code ninja rockstars" fresh out of school - simply a brave face in a macho subculture, or is it the Dunning Kruger effect

How about the bravado of the startup "code ninja rockstars" fresh out of school - simply a brave face in a macho subculture, or is it the Dunning Kruger effect at play, because they haven't had the chance to work alongside experienced colleagues that make them realize they have more to learn?