But airing Trump during media time slots is different. It’s ostensibly the news, but in reality it’s an event people tune into specifically to watch. Broadcasting a Trump campaign rally or a rambling Trump press conference draws people who are interested in seeing an extended look at what this controversial political firebrand is up to. This means people will likely pay more attention to a Trump broadcast feature than they would a Cruz TV spot.

The media networks and outlets know this, which is why they handed Trump nearly $2 billion in free coverage: it gets the ratings up and the magazines off the racks and the clicks on the websites. Trump knows it, which is why he continually topped himself in craziness throughout the campaign. The cameras would turn to him, the people would watch, and Trump wouldn’t have to spend a dime. It worked. Trump is the GOP’s presumptive nominee for president.

What are the lessons to be learned here? There are two. The first is this: Trump is probably a far weaker candidate than anyone, even Trump himself, realizes. Without the sustained media blitz, he likely would have flamed out last year and faded into irrelevance. Now, as a general election candidate, the media—the members of which are overwhelmingly liberal—may turn on him. He may lose the free coverage, or the coverage may turn hostile and unwelcoming, at which point he will be without what was likely the key factor in his success over the past year: no-charge, friendly media.

The second lesson is this: the Democrats are wrong. Citizens United did not unleash an army of election-buying billionaires on the country.