I think some people are mistaking Presbycusis for environment induced hearing loss.
Regardless of whether you protect your hearing well or not, you WILL lose your full frequency range over time as you age. This is Presbycusis.
The noise induced hearing loss we get from being exposed to loud music/noises starts to first to affect the high and upper mids (3-6KHz), and then slowly moves to lower ranges of the mids.
So basically, even if you're 50 years old and can only hear up to 15KHz and protected your ears well and have a very flat response in your hearing, you can realistically hear better than those fucking retards in their late teens who have been exposing themselves to super high volumes everyday because of their portable music player for years yet can still hear 20KHz.
This is the reason why many of the older mixing and mastering engineers are still doing great work, because they protected their ears and their mid range perception is still relatively intact, despite perhaps only being able to hear up to 14 or 15KHz.
Of course, that's not the sole reason why they're good at what they do, but obviously not having to compensate for hearing damage is a HUGE advantage in the same way having a good monitoring environment is advantageous over a shitty one as they don't have to compensate for limitations.
My sister is only 4 years older than me, and her hearing is pretty fucked already. She has to turn up the TV louder to compensate for the damage in the mid range she has caused herself by never wearing ear plugs by playing drums and going to heaps of gigs without hearing. A lot of people underestimate just how quickly that damage can accumulate.