You will have to ask black people why they celebrate "Juneteenth" by shooting each other with illegal handguns. I agree that it's really stupid and self-destructive.
As for data on the "typical mass shooter" you will have to take up the argument with the NY Times, the favorite news source of the left.
This NYT article is based on a Times study of mass shootings. As with one-on-one gun violence, young black males with illegal handguns commit a wildly disproportionate share of mass shootings.
Most shootings with four deaths or injuries are invisible outside their communities. And most of the lives they scar are black.
www.nytimes.com
...The divide is racial as well. Among the cases examined by The Times were 39 domestic violence shootings, and they largely involved white attackers and victims. So did many of the high-profile massacres, including a wild shootout between Texas biker gangs that left nine people dead and 18 wounded.
Over all, though, nearly three-fourths of victims and suspected assailants whose race could be identified were black. Some experts suggest that helps explain why the drumbeat of dead and wounded does not inspire more outrage.
“Clearly, if it’s black-on-black, we don’t get the same attention because most people don’t identify with that. Most Americans are white,” said James Alan Fox, a professor of criminology at Northeastern University in Boston. “People think, ‘That’s not my world. That’s not going to happen to me.’ ”
Michael Nutter, a former Philadelphia mayor, who is black, said that society would not be so complacent if whites were dying from gun violence at the same rate as blacks...
...The Times compiled its list of 358 shootings with four or more casualties from largely crowd-sourced lists managed by the social media network Reddit and Gun Violence Archive, a nonprofit organization. The groups recently combined their efforts at the website gunviolencearchive.org.
Four or more casualties is a far broader measure than “mass shootings,” which are commonly defined as the killing of at least four people, not including the attacker. But it captures many victims who some criminologists say are too often ignored: people who might have died given a slightly different trajectory of a bullet, or less-sophisticated medical care.
Counting assailants among casualties increased the total number of cases by fewer than three dozen, most of them domestic violence shootings that ended in suicide. Hispanics were not separately identified, because police reports do not systematically identify victims and suspects by ethnicity, only by race.
