“How does the media know who to provoke?”
They don’t have to pick. They just need to advertise.
Disturbed? Lonely? Nobody cares? Misunderstood? Angry? LOOK AT THIS, we’ll show what happens when YOU do something EVEN WORSE than what we are showing you now! Want 24/7 attention? Want the President to speak your name? Want every newsroom in America speaking your name several times per day, as we try to analyze and understand everything about you? Hey, WE can make you more famous than whatizname that shot John Lennon! Here is a list of weapons you’ll need and don’t forget we’ve been saying for two decades now that an AR or AK is “powerful”, so powerful the POLICE will fear you!
That sort of blanket advertising.
Economically, they’re just satisfying a demand.
Look at how desperate people are in the Breaking Threads here for the name of the perp, and any information about them (particularly when the information serves whatever political/religious/drug axes they wish to grind).
Nailed it.