“Do we really need to own guns?”
Ask the Jews of 1930’s Germany.
For you lib-lurkers I'll break it down in very simple terms. Think of it like insurance. You have life insurance - never used if you're reading this. You have car insurance, homeowners/renters insurance. You probably have a smoke detector, a carbon monoxide detector, and a fire extinguisher in your home. Your car has 5mph bumpers, you wear your seatbelt, and your have airbags. You go to the doctor and dentist regularly for preventative checkups.
How often have you used any of these, really? We do a lot of things to avoid and/or reduce risk.
So when you want to know why some people like to be prepared to defend themselves, ask why you do all these things. Because you have to? Because you want to? Because the consequences of not taking these precautions are too severe? Same thing with owning a firearm and learning/training to defend yourself, your family, friends, neighbors, and innocent bystanders. On top of that it is just plain fun. Some people work at that perfect golf swing, or tennis lob, volleyball dig, bowling toss, baseball pitch/hit, slapshot, etc. Some people are looking for the perfect sight picture and trigger pull.
Or for more fun, turn the question around. Why doesn't every responsible adult have a firearm? If a crime happens to you or in front of you to someone else, are you going to stand meekly by and let the low-life scum get away with it? Are you going to try to stop it? Wouldn't you want bystanders to help you? Well, you want to wade into a situation bare-handed or with an advantage? (or if the criminal is armed, on even footing) What are you, sheep to be led/slaughtered, or Americans in control of your own destiny?