I can attest making a mistake in front of a classroom is very very uncomfortable. But one never forgets, and perhaps the class seeing the teacher being humbled might even be beneficial for them.
If you need another reason to go speak at your local WordCamp or Meetup Group, try this one on for size: do it to learn something new.
I stumbled across this article from 2011 where Annie Murphy Paul talks about why we learn more when we teach. There’s a deep level of satisfaction derived from teaching that is hard to get any other way, and it drives us to become experts in whatever it is we are sharing with others.
So don’t just teach for others, teach for yourself, and apply to speak at your local WordCamp!