If you have done your homework, purchased the proper weapon for your needs and been thoroughly trained in not only its use but the applicable law you now have an option that the unarmed do not. It is now your choice when confronted with a threatening, often rapidly deteriorating situation whether or not you will utilize deadly force. In all situations I for one, like to have options.
Most folks are all for law and order but get a little squeemish when it comes to chapter and verse. As pointed out calling the police may be the right thing to do but most of the places we camp are 30 minutes to an hour from any sort of police response.... if your cell phone works.
We have been to a nice campground where campers were murdered, their trailer burned to the ground and their vehicle stolen (Near Greer Arizona). At another the host was attacked by a rabid bobcat and severely bitten(Peppersauce CG outside of Oracle AZ). My bride and her friend walked right past a mountain lion that 30 minutes later lay dead (shot by a Ranger), after it threatened a man and his young son (Ventana Canyon, Tucson AZ). I was accosted in a gas station by a couple of locals begging for money (just off I-40 in NE AZ). In every one of these scenarios a weapon in the hands of the well trained either did or could have made for a better outcome. If you don't think things like this happen or that they only happen to others you might want to think again.
Everyone has to find their own comfort level when it comes to weapons but if you choose to have one you had better be prepared. My Concealed Weapons Permit instructor stressed that every bullet leaving your gun comes with three lawyers attached and none of them are your friend. If you are going to have a gun you must be wiling to use it without hesitation and be skilled enough to do so competently. This involves not only taking classes but lots of ongoing practice. If you are not willing to do so then maybe a gun is not the best choice. As always... Opinions and YMMV. :C