I think your observation about age is normal. With a few exceptions riding or rebuilding motorcycles is recreational, not generally a persons primary means of transportation. As people age or settle into a mature lifestyle there is a little more time and probably more expendable income for motorcycles.
I see a lot of young riders but most are sport bike types. As they mature they move into tourers, cruisers, dual sport, and a few of us into classics. I was lucky, I started riding at 14 yrs old (newspaper route on a 57 Cushman Eagle) and have had bikes of some form ever since.