I'm 35 but just recently in the last year really got back into mopeds. I dabbled a little in my mid twenties but then had to sell the two bikes I had when I moved overseas.
I always wanted to get another bike when I moved back to the states but honestly couldn't really afford it until I went back to work a year ago. Was a stay at home Dad for almost 5 years.
As cheap as mopeds are initially they can be super expensive once you get deep into the hobby. I can see that as a reason a lot of younger kids don't get into it. If you are looking for a cheap reliable form of transportation a 30-40 year old moped probably isn't it.