Why does it have to be a competition. Shouldn't it be about being able to help and contribute. Too much focus on efficiency and not enough on well being of society as a whole.

80 year olds with a desire can still contribute. It doesn't have to be in competition with 20 years.

IME almost all 80 year olds can contribute much more than 20 year olds for any mental task, beyond super-demanding cognitive work like high-level math or some coding.

My point isn't the competition, it is the fact that there is a physical decline with age that no amount of training can offset, which you can observe if you compare to a 20yo. I think it is the same with the brain. And like for every large population it is a distribution, there are always outliers. But not many.

Sure. And I agree that you "can't defeat nature" in the end, but at the same time, that's no argument against fighting it tooth and nail, right down to the bitter end, staying as fit as possible, both mentally and physically. :-)

And average 50 year olds.