Although many of the older folkies have been involved since they were in their teens or twenties, there's a sizeable proportion who haven't. I'm one of many (and I could name dozens) who didn't really have the time or inclination to seek out folk clubs and sessions until the age of about 40. Many people in their 20s and 30s are too busy with careers, families and other aspects of their social lives in their 20s and 30s, and in any case they may prefer not to socialise with their parent's generation. Once they approach middle age, they often become more relaxed about this and may have more time to develop their own musical interests, perhaps taking up a new instrument or singing.

So what I'm saying is that although some of the "original" folkies who were prominent in the revival of the 1960s and 70s are beginning to lose interest/marbles or simply die off, there's also a constant flow of new people into folk clubs, sessions, festivals etc - not necessarily young people, but new recruits of all ages.