A lot of these mass shooters (and a number of serial killers) quote social Darwinism nonsense as inspiration. I wonder why that ideological portion is not being dealt with more. I hear social Darwinism ideas fairly frequently in everyday conversations with people, like casual lunch conversations.
It is not individual Darwinism but social Darwinism. They think they are part of a superior race, and so it does not matter as much what happens to them individually.