The logical comparison is not between the group of all those who carry guns and the group of all those who don't.
It's between the risk for a particular individual of choosing to carry or not. Fairly obviously, those who choose to carry are more likely to be in dangerous situations, which is WHY they choose to carry.
Congratulations, you can spot the reverse causation aspect that the author of this drivel can not.
The control group were people they matched for age, race, income, sex, and being in Philly at the same time as those injured in an assault. They got these “Control participants were sampled from all of Philadelphia via random-digit dialing.” Also, “We did not pair-match case participants and control participants on location.” So, they just randomly called people to find controls, and their controls could be anywhere in Philly at the matched time of the shootings.
Also from the article:
“However, compared with control participants, shooting case participants were significantly more often Hispanic, more frequently working in high-risk occupations(1,2), less educated, and had a greater frequency of prior arrest. At the time of shooting, case participants were also significantly more often involved with alcohol and drugs, outdoors, and closer to areas where more Blacks, Hispanics, and unemployed individuals resided. Case participants were also more likely to be located in areas with less income and more illicit drug trafficking (Table 1).”
A lot of these cases were not surprise assaults, but came from “arguments” - “...many of these events were 2-sided situations in which both parties were ready and mutually willing to fight on the basis of a prior argument.(29,3)”
From this, they get that people who have guns were 4.46 times as likely to get shot than those who were not armed.