“A standard tournament with 100 golfers playing a 165-yard hole with a $10k prize sets an event back ~$235.”
An amateur hits a hole-in-one about once in 12,500 tries. That is rare enough to sell as a long shot and common enough to happen every day somewhere. One Reno firm insures about 15,000 events a year and has paid out around $56 million since 1991. The charity gets a flashy prize to advertise, and the insurer gets paid to bet against the crowd.