I think I used to be one of them in my mid 20's. When I was pregnant I started getting a grey hair here and there and would freak about it. I was probably the only one who could even see them!
Now I realize how silly it was, but those first grey hairs are stressful! LOL I do agree that it's annoying though now that I'm older to hear twenty-somethings complain about grey hair and wrinkles. I just want to say to them "JUST WAIT! That one grey hair and your perceived crows feet that you have right now is NOTHING!".