Knowing everything

It is impossible to know everything.

I remember a professor saying the most important benefit of getting a degree is not the knowledge. It's knowing how to find the answers.

Working in HR, managing an office, or running a business are perfect examples.

At some point you will be asked a question you can't answer.

It is perfectly natural, and has nothing to do with your qualifications. It simply means you want to be sure to get it right.

Here is an encouraging thread on Reddit.