Why was Fox News so able to induce such hysteria in these people, though? (Admittedly, that's less comfortable to think about than just complaining about what Fox does.)
With current long lives, lower crime, domestic peace, reasonable prosperity, and social insurance, there's a lot less to genuinely fear, in the US, than ever before. Without the challenges and stresses of full-time, market work, the retired are especially lacking in 'common project' or 'tribal team' fears (as opposed to say personal-health or relationship fears).
Politics, among other industries, competes to answer this craving for objects-of-fear. The cable-news/permanent-political-campaign/crusading-government-busybodies nexus is an extremely efficient, low-cost, high-emotional-salience provider. Small staffs, recurring themes, and grandiose good-vs-evil narratives can be constantly redeployed, as a neverending modern fairy-tale with the added sheens of 'reality' and 'import'.
Compare also: the hygiene hypothesis, for how an immune system unchallenged by real threats may tend towards misguided allergic or autoimmune overreactions.
http://en.wikipedia.org/wiki/Manufacturing_Consent:_The_Poli... covers the how.