I believe everyone who has a sound mind should be able to carry for self-defense, not only of himself / herself, but of his/her family and nation.
Lets play out a thought experiment. Its World War 2 and the Nazi's are mass murdering Jews again. The American troops at Normandy storm the beach, only this time, they have no guns.. how would it turn out?
Well as it turns out, we do know how it would turn out. Russia literally sent MILLIONS of men, around 20+ million to rush the Nazi Germans defensive live when operation Barbarrossa commenced. The outcome? 20+ million dead Russians and hardly a dent in German defenses.
This world is evil and evil people will always be here, that is why we have guns. Not to murder or kill, but to save lives from evil men and women.