gliding attracts plenty of people - and then loses them again. ....
the attrition rate for those who do join is dreadful.

This is a long standing (and known) issue in the airplane training
community, although I expect it's worse in gliding. From the National
Association of Flight Instructors
http://www.nafinet.org/news/2002%20-... o%20FAA.html
-

the new US sport pilot rating: "Lower entry barriers could reverse
the long-standing dropout rate of student pilots"

and

"A major problem in flight training is the “drop-out” factor; a
situation that sees many people complete a few hours of training,
perhaps even through solo flight, then lose interest. We need to uncover
why that occurs and take steps to remedy it...."

Tony V.