The inexperience and hubris of youth. We all have this to varying degrees, but those entirely new to the field for whom it is their first profession have it in

The inexperience and hubris of youth. We all have this to varying degrees, but those entirely new to the field for whom it is their first profession have it in spades (that's both a gift and a curse; great things are built by "naïve" trailblazers).