Surveys of criminals show that they tend to avoid targets they feel might be risky. But ultimately this argument fails, even in principle. A central tenet of game theory is that attackers have the advantage over defenders. A defender must defend against all possibilities of attack, and in doing so defends none of them very well. An attacker has to choose only one line of attack, and therefore can do it extremely well.
Attackers have the advantage of surprise, planning and initiative.
An example is a careful, well-considered plan to shoot someone in the back, even if the person is openly carrying a sidearm. Another example is bank robbery. A useful analogy here is war. The fact that the entire world out-armed Hitler did not stop him from attacking it. Furthermore, even the certain threat of retaliatory force will not stop someone whose senses are impaired by drugs, alcohol, jealousy, anger, insanity, pathology, self-destruction or deception.