You're wrong too about social dancers. Competitive couples are the most capricious students of any teacher/coach. They are always chasing rainbows, moving about, and blaming everyone but themselves for the fact that they never get beyond the first round.
Social Dancers represent 90%+ of the dancing community, and 90%+ of the income of the majority of dance teachers. They come back, year after year. Sometimes we wish that they wouldn't, but we take their money, and smile.