I think we are like AlphaZero. We play chess (or go) with ourselves, in our dreams. That's how we learn. We create our own Microsoft Flight Simulator and step in it, and "fly". And crash. And crash again. That's why most dreams are quite unpleasant. If you don't crash in the simulation, then the simulation was not all that useful.

PS: If you want to create an AI_Zero that creates its own simulation and plays in it to train itself, go for it. Just come back to Hacker News and tell us about it.

This is the more interesting question, I think. 30+ years later still having dreams about exams for classes I forgot to drop, exams I didn’t study for, etc etc.

Having dreams about upcoming exams seems obvious compared to why a lot of us have dreams years and decades after your college years are over.