HN user
I usually reply with something similar to this. I try to remind them that the definition of "wrong" has evolved over the course of history - sometimes dramatically and quickly.
The things you freely discuss on on a platform today could become socially unacceptable tomorrow and evidence against you the day after that.
I experienced much the same thing when I first discovered HN. What helped me was the realization that there's a difference between being aware of something and being an expert in it.
I've found that it's not often that I need to be as intimately acquainted with a subject as those who are feature on HN appear to be. In fact, just knowing about something has been enough for me to intelligently answer an interview questions, converse with a senior engineer, or make the right decision on a project. And usually that's because what's most important is being curious and asking questions - e.g. admitting to myself that I'm not an expert.
Now, instead of being a testament to my ignorance and personal failings, HN is portal that let's me feed my curiosity.
You may want to do some research on the impostor syndrome. It's been my experience that anyone who's any good at anything is convinced they'll never "catch up."