No they are not rare
He’s not talking only about massacres in gun-free zones — such as schools.
But also the insane violence among kids in many cities and suburbs — especially black areas: about 30 young black men die everyday by way of violence, amid the drug gangs, serving their druglords.
That’s why Grossman says: GANGS ARE THE FUTURE.
Shootings where a teen kills a large number of people (more than two) with a firearm are indeed rare by any measure. But they are even more rare when one considers your premise that they are driven by video games. For example, Call of Duty: Modern Warfare sold 13 million copies, not counting piracy. If we could tie even 13 mass shootings to it, that would mean it was less than a 1 in a million risk. Can you point to 13 mass shootings that have occurred since 2007 and prove that this game was a major factor in them? Unlikely, and that's just one game. Halo 3 sold 11 million.
It's true, as you say, that Grossman is not only talking about mass shootings in schools. But what's foolish is that you're taking a group of people (urban gang kids) with pretty much every single pro-criminal indicator in their life you could ever come up with-- poverty, poor education, absent fathers, fathers and older siblings in the prison system, drug use in their immediate environment, glorification of gang and drug activity in their musical culture, welfare culture, etc.--and blaming their behavior on a game that is also played by legions of non-gang kids who don't have any of those indicators and never kill anyone.
If you really think that the violence in the black community is being caused by video games instead of liberal policies and lack of father figures, you need to explain why the kids without those problems are also not killing people. You need to explain, for instance, why a Boy Scout troop in my area has an annual cabin campout where they spend the whole weekend playing these games, and not a single one of any color has been in trouble with the law, much less shot another person. You need to explain why Chicago has twice as many firearm murders as Houston despite being the same size and racial mix...did Halo 3 and Call of Duty sell twice as many copies in Chicago?