Unfortunately this is a not unknown occurance at ranges that rent guns and most every range now it seems does not allow gun rentals unless there is two people or more desiring to do so or if you have your own gun already. Happens about once every year or two at some range in my area.
I unfortunately had to be involved with one such incident, was not as bad as I thought it would be legally and all, but I felt bad for the patrons who witnessed it and range was only closed for like 3 hours because of it.
Unsafe too, bullet could have hit bystander if not for protective barrier between lanes and fact bullet lost velocity. I heard a rumor one range in my area had a very bad problem with it and actually had a roll out kit for such a thing, mops, kitty litter ect. Very selfish as mentioned, if you want to kill yourself, why make others suffer with you that have nothing to do with your problems?
I think that was BS though as the cops were adamant we were not to clean the mess and the city sent a hazmat crew to clean it and they did not even get around to billing for it. I'll spare you all the morbid details but it did not cause as bad a mess as one would think, probably depends on caliber of weapon though and bullet placement.
One more example of handguns not having muchpower,guy in my case did not die right away even after high caliber handgun shot to head. If a handgun fails to immediately stop someone with a headshot who wants to die, how is your handgun going to perform on a young, drunk or high assailant who wants YOU to die?