Fox News is “mainstream” only by the modern and severely diluted definition of the term; Walter Cronkite once pulled audiences in the tens of millions. By any reasonable calculation, Fox News is niche. And its niche is old white men. Cable news is a gerontocratic kingdom where Fox News serves as king. The median age of Americans watching CNN, MSNBC, and Fox News is over 60. Half of Fox News viewers are over the age of 68.

Television is particularly popular among men, people who didn’t go to college, and people over the age of 70, which is a great description of a predictable conservative. (Retired seniors watch more than 50 hours of television a week.) Indeed, this older male group is not only ready-made for cable-television-viewing; it comes prepackaged with extremely conservative views. Over the last three general-election cycles, the 65-and-up group voted for the GOP presidential candidate by an average of 9 percentage points.

This is Fox News’s secret sauce: not production values, personalities, or entertainment, but demography. Old men are the most dependably conservative of any age group, and old men watch the most cable news of any age group. Fox News’ core demographic—and, by the transitive property, its success—is a fortuitous alignment, the perfect captive audience for an interminable documentary of the conservative outlook on American life.