It's a fascinating read. Well worth the length, assuming people can put their partisanship aside long enough to digest it.
Essentially, Trump's major claim to fame and credibility is his savvy deal making. But that entire claim is based on 30 years of lying about his actual assets, profits, debt, etc. Essentially, he has never been worth close to what he claims. More importantly, the vast majority of his wealth is essentially his inheritance from his father, which he didn't receive until 1999, years after his fame as an extremely wealthy and successful business man became entrenched in American psyche.
As a country, we've essentially elected someone in part on an erroneous belief that he had built significant wealth for himself over the years through savvy deal making. In reality, he's far less capable at the one thing he's supposed to be good at than we've realized.