The logic is this -- it's like any other crime. The bad guys need the "perfect storm" of motive, means and opportunity. You can stop a crime by denying them any one of those ingredients.
I guess we should all live in a fortress and never leave.
Opportunity - the minute you leave the house.
Motive - how do you stop or inhibit another's motive.
Means - Anyone with the desire will acquire the means. Again, how do we stifle their acquisition of the means to commit a crime?