The Las Vegas killer’s motivation(s), says Dalrymple in City Journal, will never be understood:

Whatever background factors supposedly contributory to his commission of an atrocity are found, their explanatory power is almost certain to be minimal, because the number of people who share them, and yet do not mow down people from the heights of hotels in Las Vegas, is likely to be large, possibly vast. In any case, the connection between such factors and the behavior in question is very far from a Euclidean proof. How does a disturbed childhood, a failed love affair, low self-esteem, or whatever else, lead to the murder of 59 strangers?