I don’t think it’s being oblivious.
It’s being removed enough to forget the painful parts, but being aware enough at the time of the good parts.
The painful parts decay faster than the good part memories, but schooling pain lasts forever! So the crossover seems to be in people’s early 20s
Being objective about your personal history is really hard - but it drives a lot of decisions today, so it’s good to at least revisit those “good times” to put them into the relevant context (too few people do this!)
“Oh pity us, we got it so bad and they didn’t!!!”