But you're trying to equate "statiscially more likely" to "explains whe itts neve rhappend". The ONLY way you can do this is to compare the sttictial likely hood to the number of people involved -- someting you cannot do.
Any person is just as likely to be a target as any other person; the only difference is where that person is likely to be when the killer chooses to engage. The killers do NOT choose to engare at places where there are lots of people with guns. Why?
Prove that anyone at any time at any place can be a target?Prove it.
This proves itself.
Prove that there is a reason why the killers do not choose to engage their targets where there are also large numbers of guns?
Easy: it hasn't happened.