Club members who treat it as a club
But not all flying schools have clubs or are clubs.
Yet I think what makes a good flying school is the presence of post-learning pilot support that may involve mentoring and/or a referral to one or more home-based flying clubs or groups... as well as the sociable aspects of the school.
Organized day flyouts or week-long vacations which give pilots some time to fly and other times to enjoy their destinations is something that keeps people flying.