Well, out of the 8 or so people I did my PPL at Ormond a couple of years back (all under 30), I'm the only one who flies now (but now over 30).
The rest are too busy/not interested/can't afford it.
I imagine there's a strong "get the ticket" goal for younger people starting out, but once the realities of cost, maintenance of the licence, medical and availability if not in a group coupled with the UK weather, it's more trouble than it's worth.
(The general unhelpful attitude towards GA at the UK's international spaceports doesn't help either.)