The hardest part of teaching is it's impossible to remember what it was like to not already know something. You can't un-know it so get back your previous perspective. So, you forget all the things you take as known.

This is the problem I find with the 3blue1brown videos. They're pretty but I never get any understand from them. To people who already know they nod and see all the concepts they are already familiar with shown in a neat way but to some (like me) they don't generally get me to understand. Too many pre-reqs or someting