For anyone interested in long-term involvement in the sport, there is much more to judo than "just" competing.  Coaching and refereeing are both activities that many senior players move into as the lure of full-on competitive judo begins to lose its attraction.

There are also ways in which you can actively participate in the sport without even setting foot on the judo mat.  Many parents who are not themselves judo players often get involved by being recruited as table officials at their own club.