Your criticism assumes the person with the gun is responding to the attack, running toward the sound of the gunshots.
Concealed weapons aren't for responders. Concealed weapons are for the targeted, intended victims; the people already present when the attacker begins.
This chart includes only those scenarios where a criminal attacker was not stopped before firing their first shot, and was not stopped until they had continued shooting long enough to be grouped with the rest of the attackers on this chart. It includes only people who were allowed to continue their attack long enough to qualify, and does not include attacks that were prevented entirely, or were stopped before reaching the chart's threshold.
The chart also fails to address one of the main reasons why so many of these shooters decide to stop shooting and run away: how many of them saw guns in the hands of their intended victims, and left before those victims fired a shot?
True, but largely irrelevant to the issue at hand: It turns out that "electricity" is yet another thing that a needy individual can acquire with "money".