I'm sure people tell themselves it's safe as it's unloaded when you start, and pointing away when the spin is finished. Looking at a pair in slow-mo, looks to me like the lever closes and it would be good to fire about the time it's pointing at your knees

You can't teach stupid, but it's a popular self-taught subject in the old US of A obviously

Skip to about 2 minutes - https://www.youtube.com/watch?v=1BxbTSaxduA