GP didn't mention degrading retinas, just age. I'm over 50 and need glasses but, while acknowledging that life is a one-way journey, I just don't like people talking like ageing is necessarily this slide into decrepitude after 40.
The vast, vast majority of people in their 40s (wearing appropriate glasses if necessary) can tell the difference between an average monitor and a 4K display, which is the context of their comment.
Putting a very fancy lens on a 0.3MP sensor doesn't give you higher resolution photos.