And they do so for the same reasons: (1) because they want to keep their power (knowledge is power) and (2) because they know they won't suffer for their lies.
of course
VDH had a great article the other day about why a culture of hate has grown; a leftist culture that smears Trump voting middle America and spews anti Jewish and anti-white vitriol with impunity. The answer to why this happens is your reason #2; there is no consequence because the media supports them.