Because progressives dominate 90% of media outlets and studiously ignore major stories like the IRS scandals, Benghazi, and basically anything harmful to Democrats, Fox News is handed the opportunity to reach the public with distinctive content unavailable elsewhere, and the public is responding.
Most major media would rather be progressive than successful. But then again, progressivism almost never works as it promises, based as it is on a false notion that human nature can be perfected with the appropriate institutional arrangements (including, of course, a media structure that plays along). CNN and MSNBC prefer to live in that make-believe land, and are suffering the cosequences.
Almost certainly, the widespread disillusionment with President Obama, who also lives in the progressive bubble where if only we make nice to Muslims they will be friendly, tolerant and peaceful toward us, for instance, is contributing to viewers shunning the prog cable news outlets.
Progressives’ chickens, as Rev Wright was wont to say, are coming home to roost.