Because CNN reports news. It shares that endeavor with dozens of other NEWS AGENCIES, so the audience is all divided up between them.
Fox News is not a news outlet. It states that clearly in its own mission statement. It is an entertainment orginization. It literally makes shit up completely.
It is the only "news" organization on the planet that does that, so all the cool aide drinking, shit-for-brains, sleeping with their sisters, looking out for UFO's, uneducated, racist morons flock to it like moths to a porch light.
That's why.
That is typical of GOP morons: they actually think bragging about not reading makes them cool while not realizing it simply proves how uneducated, racist, ignorant and moronic they are.