From The Atlantic:

Most people in the United States, allowing for wild variation in race, class, and education, are victims of violence only very rarely. Watching the videos, however, invites you to simulate violence at an extraordinary rate, much higher than we are mentally equipped to manage. (Correia himself has seen tens of thousands of them, and he posts a new one to his channel about once or twice a day.) The effect of these videos is to habituate viewers to that violence, to train them to imagine themselves in it. Training yourself to imagine something makes it seem more likely to happen, and primes your instincts to react to it—and, I suspect, initiate that violent reaction and overdo it when circumstances could be resolved more peacefully.