Uwe, from a financial standpoint, I would argue that the pranksters deprived the golfers of the privilege they had paid good money to enjoy: a relaxing round of golf. The value of the round of golf of which the golfers were deprived was greater than the value of the RC car.
Also, the swinging of the club was not in response to the car, it was in response to being charged and sworn at by the "pranksters". The confrontation was initiated by the kids, I would argue the poor, frail (though speedy) senior was merely defending himself. And no one was hit or hurt, to imagine what might have happened is pure speculation. And I'm sure you know that the "I've done worse" argument has no legal standing.
From a social/psychological viewpoint, I would agree that the old dudes over-reacted and it was bad form. But was it criminal? No way.