@lpskier and @Clydesdale have it - at least for the teen competitor. My son, who has the competence @Luzz found to be important (national level skier) and identifies with the competence he has in the sport is increasingly driven by the author's point #10, Social programs - he continues to ski because he has friends who ski. If he didn't have several skiing friends who attend tournaments, I believe he would not want to ski. While he practices to achieve the competence, I believe he finds his identity in the sport from the social relationships *and* the competence. At most tournaments we see our son for 5 minutes at each event and then he is gone. On the golf cart with his friends, riding bikes with his friends or whatever else catches his eye.
Teens are driven by their social relationships - so making skiing social is extremely important to prevent the "tumble," at least in my opinion. Camps, social events all are an important part of retention for teen athletes. Heck, even inviting his non-competitor friends to ski or wakeboard or surf with us helps prevent burnout and loss from the sport, but I have no idea how to do this on a wider level. Make some rec pulls at smaller tournaments for a chance to wakeboard or ski on two skis? Something to bring out the non-competitive friends and keep teens social, perhaps? I truly believe we need to find a way to draw more teens to tournaments to make them as social as they are competitive.
As my wife often says - we can't keep thinking that what worked when we were kids 30-50 years ago is going to work today. The days of "because I said so..." are long past.