I have heard the statement young people quote about the lightning reflexes that they have, to get them out of trouble.
Lotsa crosses along the side of roads don't seem to back that theory up.
One of the only places they really count is in fighter aircraft and car and bike racing.
Flogging around in commercial aircraft never gives those reflexes a chance to be used. The aircraft and pax couldn't handle it.
The experience pilots gain over a career slowly give them the rat cunning to see the problem arising and avoid allowing the holes in the cheese to line up.
Till one gets slow, forgetful or just plain sick of the cr@p we are dealt as time goes on, an older pilot is better than a sprog because he has time to pass on the cunning.
One could write a book, but being in the situation really sinks in much more than reading about it regularly.
I think its a combination of keeness and medical condition that governs retirement.
You young guns; WE'VE been you, wait your turn. You'll be us one day ... if you're lucky.