Sheesh.....quite a few great replies.....no good way (for me) to copy all good links........

I will agree with some on "time being an issue", throw in "outside influence".

Per "the real UncleHank" and others, I know of at least one junior club member, in my club, that received a one year scholarship. Basically, you show up, dues and flying are paid for. This to a kidlet that did first glider flight at 6.5 weeks (yesssssss......weeks....not years....) old since his father was a CFIG at the time.
Had older generation family for training and gliders to fly.

In general, no family killing the desire to fly....gliders or otherwise. At least 2 family members that were current CFIG's.

Time became an issue.
Other endeavors ate time.
Eventually, one student could drive himself all of maybe 40miles from home to Gliderport.
What more do you need to do?
Basically free flying, multiple peeps to get younger person from home to gliders and back, we stop short of pressure to fly as well as wiping their butt when they poop.
Yes, I wiped their butt of poop when they were really young.

I have zero clue on a good answer, I can only state what I have gone through or supported over 4 or so decades.

A small handfull in this thread know EXACTLY what I am posting and know the history.
Wish I or others had the majic bullet to raise membership in the US SSA......