The OP’s question was more about where are all the young people in folk clubs? It’s true, not many in the audiences unless their pals happen to be performing on stage, and then they’ll hope to get in free on a “guest list”! The whole age spectrum of folk club audiences has changed since the “folk revival” of the 1960s when it was young people who started up, organised, attended and performed in the many folk clubs then. The people themselves are the same ones, only now 50-60 years older. “Succession” has been a problem in keeping some clubs going; no-one younger volunteering to carry on when these older folk want to step down, or are forced to do so by illness, infirmity or the inevitable. And so another club dies.
As Al and others have said, there are plenty of talented young musicians about, but they seem mainly prefer playing in pub sessions or hoping for paid gigs in clubs or festivals rather than spectating or helping to run clubs. (Of course, there are a few notable and commendable exceptions to any such sweeping generalisation, and some are involved in teaching yet more budding instrumentalists.)
In our area, we are lucky in having a good number of thriving folk clubs, and they have largely survived the Covid pandemic, most of them beginning to meet in person again : some of them shut down for the duration, others continued on Zoom, Facebook, etc. But there are certainly not as many as there were 50 years ago.
And even in my older age-group, I can think of some who, having learned an instrument, spend every bit of spare time at sessions but rarely attend any clubs or “spectator sport”.