[dullgiulio]

Another reason for people trying too look overly confident is when they are overly exposed over a certain topic.

For example, if you have very narrow job titles and roles in a team ("he is our DevOps, she is our architect"...) everyone will have to defend their role, often trying to sound infallible.

If instead you make the whole team responsible for all team tasks, everyone will be more open to leveraging everyone else's suggestions.