Mass homicides are horrific tragedies. Society must do whatever's possible to understand them fully, so as to prevent them. But people also need to separate the data from the myths and the social, political and moral narratives that often form around crime.
The point isn't to scare people about accidental carbon monoxide poisoning, which kills, on average, 374 people per year. Given our population of 319 million, that's a minor threat. Instead, this is to show that the chaotic stuff that makes the nightly newscasts is far less likely to kill you than boring, everyday things.