"man's willingness to harm others"................
What a crock of sh!t. I've owned or been around guns all of my life, and I NEVER have been "willing" to harm anyone. The ONLY time I would inflict possibly lethal harm upon another would be when I have NO OTHER OPTION.
The best way to prevent this is to not break in to my house threaten me or mine, or any other innocent person in my presence with bodily harm or mayhem. You know, "Do unto others as you would have them do unto you".
The use of lethal force is ethically, morally, legally, and justifiably allowed in the face of mortal danger. Self defense is ingrained in the biological code of all sentient beings, and has been since time began.
I have been in situations where I have been forced (by the actions of an assailant) to employ deadly force. Until you've been there, you do not know of what you speak, and NO ONE; you, politicians, cops, judges, nor ignorant "gun control proponents", have the right or ability to deny the ABSOLUTE RIGHT OF SELF DEFENSE.