That insight allowed him to play a totally different game in both the primary and the general election.
While the political establishment was tut-tutting over Trump's fight with a Gold Star family or his comments about the weight of a former Miss Universe, the real estate mogul was in the process of remaking how political campaigns are won.
Through a combination of a massive social media presence, his celebrity and the belief - disproved by facts, but no matter! - that he was a straight shooter, Trump took every rule of the game and not just broke it but smashed it.
All of which meant that on November 9, the political establishment was left to look at the shards of conventional wisdom scattered everywhere to try to find some meaning. And how did we do it? In most cases by falling back on the very same assumptions and analytical points that led us to miss "Donald Trump, president" so, so badly.
How could Trump chat with the Taiwanese president, breaking decades of protocol and potentially endangering our fragile detente with China?
How could he pick - or be on the verge of picking - the CEO of ExxonMobil as secretary of state?
Or Ben Carson, a doctor, to head the Department of Housing and Urban Development?
Or, more parochially for reporters but no less hidebound by tradition, not agree to have a protective press pool follow him wherever he goes?
Or a hundred other smaller breaks with "the way things are done" that Trump has engineered over the past month or so?
The simple truth is that Trump's transition process has been a logical continuation of the campaign he ran: a total disregard for the established methods and the rules governing those methods.
If you back Trump, you are undoubtedly thrilled with these moves, believing that he promised radical change in a broken Washington and is delivering on it. If you oppose Trump, you see his flouting of the established order as not only risky but deeply dangerous.
I take no side in that fight. But I do think that it's absolutely necessary to avoid using the old measures of success or failure to assess Trump. He has proven, repeatedly, that those metrics simply do not apply to him.
To continue to analyse him and his moves as we would, say, President Jeb Bush or President Hillary Clinton, is to ignore the fact that any traditional analysis of the campaign Trump ran would never have put him anywhere near the White House.
Two major questions remain:
1 Is Trump's ability to innovate in the political campaign space - that's exactly what he has done, whether you like it or not - something that can carry over to his time in the White House? Do voters want something different in a president than they want in a presidential candidate? If so, Trump's unwillingness to change could badly damage his presidency.
2 Is Trump an exception in politics or the new rule? Is it his unique combination of celebrity, social media and brashness coupled with these deeply anti-political times a one-off? Or does he represent a new normal in politics? Will the 2020 campaign be filled with Trump takeoffs - Mark Cuban, Howard Schultz, Kanye West? - or will it be the usual assortment of governors, senators and House members?
I don't know. What I do know is that Trump is like nothing else we've ever seen in modern American politics. We all need to adjust accordingly.