Trump tweets out FOX EVEN STILL. Because he knows that people are stupid and don't understand that they are controlled opposition, so he uses them to get out the messages he needs to spread.
It's the same reason he stays on Twitter, because he basically has to. If he didn't, it would diminish his reach and power.
TLDR: Because he's smart, and understands their strategic value.
Trump tweets out FOX EVEN STILL. Because he knows that people are stupid and don't understand that they are controlled opposition, so he uses them to get out the messages he needs to spread.
It's the same reason he stays on Twitter, because he basically has to. If he didn't, it would diminish his reach and power.
TLDR: Because he's smart, and understands their strategic value.