How many old people would claim that they only thought they knew everything when they were young? And it’s what they learned after that time?
Every one of us - if they're reasonably intelligent and honest.
Anyone who is honest would admit that.
There is an old saying for young people to get out there and get a job while they still know everything. Yes many teenagers think they know all there is to know but fund as adults how little they really do know. I think most of us have been through this.
I wouldn't say 'OLD', I would say 'ELDERLY'. My father is 75 and he doesn't consider himself old and he admits there are still a lot of things to learn about life itself. Yes, he did think he knew everything when he was young and now he knows a lot more. He was a Karate instructor, a photographer, a baseball coach, went regular winter mountaineering just to name a few. He was also a trucker and taxi driver and now he is a self-published author on 'Zon'.
All of them. But they are all senile so don't pay any attention.