In the past, when you saw older people (I'm really talking about much older than 40 but still), they did not wear the same type of clothes as the young people. The reason was very simple. They wore the type of clothes popular as when they were young.

Then there has been this misunderstanding that there is a special type of clothes that older people should wear, and that is what the last old generation wore, but they only did because they grew up with it.

Get it?

So, it is quite natural to still want to wear what you wore when you were young. People have done it in the past, it is the whole reason behind thinking of a style "made for" an age group.