Because there was a lot of money in it for various hucksters and moguls and authors and politicians, the conservative movement spent decades building up an entire sector of the economy dedicated to scaring and lying to older white men. For millions of members of that demographic, this parallel media dedicated to lying to them has totally supplanted the "mainstream" media. Now they, and we, are at the mercy of the results of that project. The inmates are running the asylum, if there is a kind of asylum that takes in many mostly sane people and then gradually, over many years, drives one subset of its inmates insane, and also this asylum has the largest military in the world.
But if this was a reasonably useful arrangement for Republicans, who won a couple close elections with the help of their army of riled-up kooks, it was a fantastic deal for the real engine of the right-wing propaganda machine: companies selling newly patented drugs designed to treat the various conditions of old age, authors of dubious investing newsletters, sellers of survival seeds, hawkers of poorly written conservative books, and a whole array of similar con artists and ethically compromised corporations and financial institutions. The original strategy behind demonizing the "mainstream media" may have purely political, to steer voters away from outlets that tended to present information damaging to the conservative cause, but the creation of the conservative media was also a revenue opportunity for shameless grifters from the very start, as Rick Perlstein showed in his classic Baffler piece on the snake oil-salesmen of the right.The bottom-feeding amorality of the sorts of people who sponsored the right-wing press, and the crummy nature of the products and services sold, shows exactly who was supposed to be consuming it: suckers. Or, more specifically, trusting retirees, with a bit of disposable income, and a natural inclination to hate modernity and change--an inclination that could be heightened, radicalized, and exploited.
Rather rapidly, two things happened: First, Republicans realized they'd radicalized their base to a point where nothing they did in power could satisfy their most fervent constituents. Then--in a much more consequential development--a large portion of the Republican Congressional caucus became people who themselves consume garbage conservative media, and nothing else.That, broadly, explains the dysfunction of the Obama era, post-Tea Party freakout. Congressional Republicans went from people who were able to turn their bullshit-hose on their constituents, in order to rile them up, to people who pointed it directly at themselves, mouths open.Now, we have a president whose media diet defines his worldview, interests, and priorities. He is not one of the men, like most of those Tea Party members of Congress, whose existing worldview determined his media diet--who sealed himself off from disagreeable media sources. He is, in fact, something far more dangerous: a confused old man who believes what the TV tells him.