I own a glock 17. I'm not entirely sure why I bought it. One reason is because my brother got a gun, so I felt the need to compete in a way.
the gun has a couple utilities.
If I ever need to kill myself, it offers a fairly reliable method. Although not completely reliable. Sometimes the bullet misses critical areas of the brain. If I ever get some nasty immoblizing injury, I may want to do this (assuming I'm still capable)
guns also provide a means of killing intruders. You have to be careful here, if they aren't threatening bodily harm you could go to jail. The problem with this, is it causes hesitation, which gives the criminals the advantage. This is why owning a gun is more dangerous sometimes, as they can use your gun to kill you. You can't freeze up or hesitate, or you're dead.
guns can also kill zombies or other things that may invade your home like in movies.