This was not a harmless joke to play on his group for a few laughs.
It was clearly a premeditated scheme to collect a jackpot and possible low score prize money.
Member/Member events at most golf clubs have high-dollar entry fees and high-dollar payouts.
This guy had to sneak out onto the golf course, draw a mark on a golf ball to identify it as being his, place it into the hole, return to the clubhouse, concoct the story about his sick grandmother, convince his group that he might have to take a private phone call, run ahead to the next tee to fake a shot, and then allow someone else in his group find his ball in the hole. And then, with a straight face, act surprised.
Dang! That sounds like an episode of Columbo!
The only reason we are hearing about this is because he got caught.
There is something seriously wrong with a person that would actually try to pull this off.
This might have been the only time he ever tried to perform his Golf Magic, but I would bet that he's pulled a few other slick moves in his business and personal life.