It may be impossible to prove without some ethically questionable experiments, but the evidence is still pretty strong that merely owning a gun greatly increases your chance of being killed.

I've never really understood the self-defence argument for every day living, if someone comes at you with a gun and intends to shoot you, I suspect they'd shoot you, whether or not you have a gun. The chance of you being aware of that threat beforehand, having the time and opportunity to get your own weapon, ready it for use, and then effectively use it to ward off that threat are gonna be really low, and basically all the time will be worse odds than just running away. Add to that the pretty high chance of being shot with your own gun in the first place, and I very much question that it improves your odds of surviving any given year.