Understanding the question gives the answer!

I have a friend that keeps asking ME the same question over and over.

'Chris,' he says 'how do you do it. How do you know all this stuff. How comes you know what I know, even though it's not your field?'

Well, I'm - ME - fed up with him asking this question (which has been going on for 15 years and more now!).

The answer is this:

If you keep asking the same question over and over, you simply don't understand the question in the first place.