It's often said the opposite of love is not hate, it's indifference.
To make someone feel truly awful, just ignore him.
If you hate them, revile them, insult them, rage against them, at least they know they are worthy of your attention, however negative.
But if you simply ignore them, they realize they are worthless--their existence has no significance whatsoever.
There is a theory that massive public shootings, starting from Columbine, are motivated by the desire to be known. Notoriety, revilement, negative attention (even posthumous) is better than no attention whatsoever. Better to be significantly hated, than to have no significance. Period.
I don't really follow the details of mass shootings very closely, but my vague recollection is that all of the gunmen have been loners, outsiders, marginalized outliers in their respective communities. This current gunman most certainly was.
We ignore the marginalized at our peril. And we publicize them posthumously at our peril as well.
May the press and public not reward this kind of behavior.