There are two types of mass shooters.
Let's call them Fred and Charlie.
Fred is angry, frustrated and wants revenge. He wants to die. He doesn't care about being famous, he just wants to cause as much damage as possible before dying.
Charlie may have some things in common with Fred, but his ego drives him to be famous. His sense of self-importance convinces him that he deserves to be worshiped, adored and celebrated. His anger stems from an unfulfilled ego and mass murder is also his way of getting famous.
The media bears some of the responsibility for Fred. It's likely that Fred got the idea of a mass shooting spree from media coverage of past shooting sprees. But Charlie, whether he's a Neo-Nazi or a black nationalist or a leftist, is very much the media's responsibility.
The media has been creating, feeding and nurturing these little monsters since Columbine. And they know that what they do will make them famous. They write manifestos and make videos because they know the media will broadcast them.
There's also fairly solid evidence that media influence plays a major role. Here's one of my old articles on the subject.
Some 200 years later, German television debuted "Death of a Student", a six-part series about Claus Wagner, a high school student who commits suicide by jumping under a train. Each episode began with Claus jumping under the train... And suddenly the number of teenage boys killing themselves by jumping under a train increased by 175%. Having failed to prevent enough suicides, the show aired a second time. This time fewer people were watching and the suicide rate for teenage boys only went up 115%.
A few years later in neighboring Vienna, suicides went up when they were featured on the front page rand fell 75% when they were pushed to the back page, run sans photos and without mention of the word, "Suicide."
Suicides spike after front page coverage of a suicide. After Marilyn Monroe's death, 197 more people killed themselves than the statistical norm. Suicides rise even after fictional suicides on soap operas. And murders are also influenced by the coverage of real and fictional murders. The rise in the number of shootings after a heavily publicized shooting isn't a mysterious conspiracy, it's Werthers being Werther or Lanza or Holmes; identifying with the method of dealing with their frustrations, if not the man.
None of this is news. The media amplifies the messages of mass killers for the profit motives involved and for the ideological agenda.
The media knows it helps cause mass shootings. It doesn't care.