Because conservatives, being foolish as they are let leftists have unchallenged control over academia/education and entertainment despite the fact that leftists have stated that they intend to take control over these institutions and even called it "The long march through the institutions" . Instead conservatives spent their time fellating the corporations. Corporations that have now turned on them.
I think you have both timing and blame wrong here.
The Progressive long march through the institutions dates back to the 1920s. The first purges were of Christian Fundamentalists who held to things like the historicity of Christ and other such basics of Christianity when you saw the
Fundamentalist vs Modernist Controversy in the American religious universities (remember most of the Ivy League schools, the most prestigious schools in the US, were private religious schools). The New York Times was shilling for the Soviet Union and acting as their propaganda arm in the
US in the 1930s, and the Soviet Infiltration of major sectors of the US Federal government was well underway
by the 1940s.
The American Conservative Movement did not form until the 1950s, with the
National Review being the foremost publication thereof and the critical publication that laid the groundwork for formulating what would become called the "Conservative" movement in the US. By that point academia was already lost to Conservatives, in fact, one of the core reasons William Buckley began formulating his core ideas was his experience at Yale, which was pushing collectivist and progressive ideology when he attended in the late 1940s, as he wrote about in
God and Man at Yale.
So I'm not sure how you can blame the Conservatives for failing to hold academia and media. They were lost long before it even became a
thing. Conservatives also long ago
recognized this loss and rather than try a counter march, which, due to the fact that there was no central authority directing efforts like there was for the progressive left in the Soviet Union, would likely have just been ineffective and end up with those who attempted making no impact. Rather they sought to build up parallel institutions, with fundamentalist Christian churches setting up their own colleges and systematically Conservative colleges being established to attempt to counterbalance things. You've probably heard of some of these
Liberty University,
Hillsdale College,
Patrick Henry College... to name just three off the top of my head. Those who didn't go that route often established themselves in public universities that were not immediately under the control of progressives, this was especially true of economics departments like that of
University of Chicago and
George Mason University (you would also note that GMU's law school is named for former conservative Supreme Court Justice Antoni Scalia), and while those still had considerable progressive presence in those schools, they have kept around some very conservative members. Using GMU as an example, a notable member of their economics faculty is
Walter E Williams who is so conservative and right wing that he's occasionally subbed for Rush Limbaugh on his show.
So I'm really not sure what more you could have asked of the Conservative movement. They have been fighting this fight for decades, longer than you've been politically engaged. When one faction has a nation state backing it and the other doesn't, the fact it has taken
this long for things to get as bad as they are should tell you how successful they have been
despite having the deck so severely stacked against them.