Sounds like a case where externalities are screwing with the decisions. If rescue costs are high but borne by the public then the jumpers are basically abusing it. But of course outlawing the activity doesn't actually stop it.

It's a lot like illegal drugs. It's a fun activity that's bad for the participants and exposes external costs on society. Seems like the standard solution of "legalize, tax, and regulate" would also apply here. Rather than simply ban these activities, maybe they should be made to bear the costs of rescue, either by putting liability on to them after the fact, or charging a fee up front.