Aristotle said, “The more you know, the more you know you don’t know.”  Albert Einstein said, “The more I learn, the more I realize how much I don’t know.”

People are experts at overestimating their knowledge and qualifications when they have little knowledge.

Olivia Goldhill, writing in Quartz:

People who are incompetent and lack knowledge in a field tend to massively overestimate their abilities because, quite simply, they don’t know enough to recognize what they don’t know. So hugely unqualified people erroneously believe that they’re perfectly qualified. (This effect that has an unfortunate tendency to create the worst possible bosses. It’s also the opposite of imposter syndrome, which describes when qualified people worry that they aren’t qualified.)