“Population Density and Social Pathology” was, for an academic paper, a smash hit, being cited up to 150 times a year. Particularly effective was Calhoun’s name for the point past which the slide into breakdown becomes irretrievable: the “behavioral sink.” “The unhealthy connotations of the term are not accidental,” Calhoun noted drily. The “sink,” a para-pathology of shared hopelessness, drew in pathological behavior and exacerbated its effects. Once the event horizon of the behavioral sink was passed, the end was certain. Pathological behavior would escalate beyond any possibility of control.
I would propose that, using Calhoun's thinking, the politically right-wing individual is more sensitive to the stress of overpopulation, and the pull of the behavioral sink. As right wingers like to point out all the time, they're also the ones with all the guns (I think this probably applies outside of the US as well). However, it might be that they're just as sensitive as anyone else, and happen to be the individuals who react to it by attacking rather than cowering. In either case, the reasonable conclusion seems to be that people will not act the way they do now once the behavioral sink is reached, and that the way that they act will be bad .
While we are nowhere near the kind of physical population density that Calhoun encountered with his rats, I don't think that's really the factor that predicts the behavioral sink in humans. It's psychological overcrowding that matters, which is surely exacerbated by the quick flow of massive amounts of information in our modern world. Personally, I feel like I'm seeing a lot of these symptoms already.