I think they just started by seeing him as amusing and, following the old adage that “if it bleeds, it leads,” covered him heavily for the entertainment value.
But it turned out they were doing free advertising for him. Trump has gotten almost 1,000 minutes of airtime, while Cruz has gotten about 300 and Rubio only about 150.
It was, in a sense, the media that turned him into the thing Americans love the best, a celebrity. And it seems to be a media agreement that celebrities are beyond reproach and beyond questioning. You’d think that when he started threatening them if the dared to ask questions, they would have fought back, but I think they waited too long to get serious.
While I do think there’s media and Dem hope that he’ll be the candidate so that Hillary can win, mostly I think it was just the American media’s automatic celebration of trash and cheesiness that got him started.
There is no question that the media and Trump have been having a symbiotic relationship. He used them to get the free feel-good "celebrity ads" focused on personality and slogans and mostly devoid of issues, while sucking the media oxygen from issues-oriented and policy-minded candidates, and the media loved the circus atmosphere and didn't mind denying serious discussions by other Republican candidates, many of which were far from the "establishment" in this cycle.
But the media also didn't mind having a chance to show cartoonishly "dirty and inarticulate" Trump as a proxy for "a Republican" and have him define / "expose" the Republicans as crude, rude, insulting, narcissistic, divisive, intolerant, unsophisticated, ignorant of issues bullies and single-issue or "he can win" voters, unserious loud-mouth braggarts with low social morals and business ethics and celebrity-starstruck rubes who fill the rallies' venues, and who will, in knee-jerk fashion, defend shady "billionaire or millionaire" with an (R) because he is by definition "successful" and thus his multiple faults (including making promises with no intention to keep them, bold exaggerations, outright lies, personal issues and [lack of] ideology) can be overlooked or ignored.
It's a win-win for them, real loss for us. Imagine how Republicans in all those down ticket (Senate and House) races are going to feel when tied to Trump if he is the nominee. And they will be asked the "Trump questions," without being able to be "flexible" (depending on the place, crowd and time of day) like Donald. Or explain the "magic" phony BBB faxes re TrumpU or faux Trump steaks, water, magazine etc.
In U.S. politics it pays (at least for a while) to be "a cross between P.T. Barnum and the Kardashians." That's why I don't dismiss out of hand Kanye West saying he wants to run for President. Actually, if Hillary were to pick him for VP ticket, she would swing a lot of certain "demographics" to her camp and would win very easily. IMHO... as sad as it sounds, but keeping with the themes of current election cycle.
Money + Celebrity = Power.* (*Ideology and reason not included.)