I'd say that the truth is that anyone who shoots strangers for no reason is mentally sick, but not everyone who is mentally sick shoots strangers for no reason.
And of course nobody who has no access to a gun shoots anyone for any reason, because he or she lacks the means. (I nearly wrote "he" there, but I think there have been three female shooters who killed several people in the USA since 1982, a total of fourteen victims.)
It seems incredibly simple to work out, to me, but apparently it is outside the mental limits of DJT.