You know, whether you like it or not, there are bad people out there who will attack you if they think you look weak. There's a pecking order to the world and the ones with the big guns think they have to go around and rub some "shithole country" into the dirt ones every 5 years.
I believe that we, as a species and by mutual agreement between peoples, must rid ourselves of weapons in order to defuse and degrade the capabilities of despots and mercenaries. But unilateral disarmament won't work when a few countries think its their civilizational duty to come and murder your mother and extract your resources.