Shut Down The Big Lie
Back in 2015 and 2016, the mainstream media gave Donald Trump's presidential campaign a huge boost. Trump was like catnip to them, endlessly entertaining, and as a result, they made his campaign a gift of hundreds of millions (if not billions) of dollars in free airtime. They'd cover his rallies in full, just to see what outrageous things he said. When the Republican primary season happened, all their questions to the other candidates were basically some form of: "What do you think about what Trump said about X?" Trump was a creature of television and pop culture, and as such understood the value of generating high ratings. And the media gleefully went along for the ride. And as a result, Trump dominated the primary and then dominated the general election.
Much later on, the media went through a bit of soul-searching: "How could we have allowed this to happen? How complicit were we in the con job?" But by then, of course, it was too late.