Ulrich this is the reason many clubs will have hefty joining fees for over 40s and over 50s to balance the reduction in revenue per round as people play more when they are older.
Not sure that I agree.
Clubs have joining fees for a couple of reasons;
1. Because they can. Most clubs can't any more because no-one would join.
2. To deter members from ever leaving as it would mean kissing goodbye to a chunk of cash. Blackmail, in other words...
As for the problem of retention of 25-40 year-old members, I advocate a 50% discount in annual fees for parents of children under the age of five. Better to keep young dads on the books rather than lose them and try to entice them back later.
There'd be good chance of getting the kids involved as juniors, too.