Think of weapons as a leverage and a neutral factor. The wielding of a weapon changes its potential for action depending on who holds it. Many people feel that it would be safe to have weapons off of the streets of the United States, but there are implications. Putting the trust of weapons into only military, police, and security officers is saying that these three somehow hold a greater power of responsibility over you, and that they can do no wrong. But the people that protect this country are not without faults, and not everyone in the service to their country walks around in shining armor.
Safety is everyone's responsibility, like it or not. Just as there are safety officers on rifle ranges to ensure that you hold your weapon properly, it's your priority to ensure that you know the powers and limitations of such a destructive power and that others who misuse this power are shown the error of their ways.
It is unfortunate that we cannot stop needless killing or the accidents that occur because of poor or non existent gun safety from adults, but life is without absolutes as far as human emotions and logic. People have good intentions, and some have bad intentions and both can and will find a way to go around obstacles that they find a problem.
So please, buy a gun and teach others the responsibilities of wielding it. It's up to you to make a difference in the world, not in the hands of a few people.