If every glider club in the US got 50 new members, few thousand total new pilots I guess. Clubs wouldn't scale to private airports with cafe's and a fleet of Duos. They'd be crushed, who is going to put in all the 2-33 backseat time to fix the world? Besides 50 new weekend punters are useful $ wise but can be more of a operational drag then boon. You really need a few that are obsessed. Preferably obsessed and having money and time, although an abundance of one can some what make up for a lack of the other.