Somebody already mentioned motorcycle riding but I also wanted to mention atv riding. Things can get awfully bumpy and if u ride hard its only a matter of time till u have some kind of crash. In that scenario I want the best retention I can get.
And snowmobiling. I have noticed over the years that what people do on ATV's and Snowmobiles would be considered reckless driving if they did the same on motorcycles and cars. So, yes ATV riders have more than their share of accidents and should consider a retention system for their handguns. Although it would be neat to be walking past the scene of an ATV accident and find a "stray", "orphan", or otherwise unattended Colt Python lying in the grass.