Now, the Republican nominee says, he's offering the same skills he used to pay less in income tax to the American public.
"I'm working for you now -- I'm not working for Trump," he told supporters at a rally in this key Western swing state Monday.
In his first day on the campaign trail after The New York Times reported
that he had reported losing nearly $1 billion in a single year in tax filings, and could legally have gone as many as 18 years without paying income taxes afterward, Trump confronted the issue head-on. He said that in business, "it's my job to minimize the overall tax burden."
"I have legally used the tax laws to my benefit ... Honestly, I have brilliantly used those laws," Trump said.
The Times did not look at Trump's federal return. It obtained one page of his New York State resident income tax returns as well as the first page of New Jersey and Connecticut nonresident returns. CNN has not independently verified the documents' authenticity, but Trump's campaign has not challenged any of the facts reported by The Times.
Trump's 1990s business failings -- bankruptcies at his casinos in Atlantic City, disastrous real estate deals in Manhattan -- were just fodder for an epic comeback, he said at a rally in Pueblo.
And any lingering questions about his business dealings and his tax returns -- which Trump is the only presidential nominee since 1976 to refuse to release -- is just a news media "obsession," he said.
He called himself "a fighter" and said he "knew that I would make a comeback, without question. I never, ever had a doubt in my mind."
"The conditions facing real estate developers in that early-'90s period were almost as bad as the Great Depression of 1929 and far worse than the Great Recession of 2008 -- not even close," he said.
Trump called the era "a bad time -- it was an ugly time. A lot of people you won't ever hear from again from that period. But I never had any doubts ... I knew in my heart that when the chips are down, that is when I perform my very best."
Trump's comments came under withering attack from Hillary Clinton, who charged Monday that Trump lived a billionaire's lifestyle while "contributing nothing to our nation."
"Imagine that," Clinton told supporters Monday at a rally. "In other words, Trump was taking from America with both hands and leaving the rest of us with the bill."
That, she said, "tells us everything we need to know about how Trump does business."
Indeed, there are still a long list of unanswered questions about Trump's finances, including whether or not Trump actually paid income taxes, and if voters believe someone who lost nearly $1 billion in one year could be labeled a brilliant.
Trump did say, though, that he pays a slew of taxes aside from income.
"I face enormous taxes -- city, state, sales, excise, employee, federal, VAT, different countries," Trump said in Pueblo.
He said he had a "fiduciary duty" to his business to use tax laws -- "or, to put it another way, to pay as little tax as legally possible."
Democrats have pointed out that Trump's fiduciary duty could only exist in his businesses' taxes -- not his personal taxes.
Still, Trump's supporters weren't dissuaded -- cheering loudly in Pueblo when he added: "I must tell you, I hate the way they spend our tax dollars."
"Put me into the board room as your representative and I will deliver for you like no politician has ever delivered, believe me," he said later in Loveland.
Trump also argued in Loveland Monday night that his handling of his own taxes matches left-leaning billionaires, including George Soros and Warren Buffett, who he said in 2014 lost $873 million.
"I wonder if they deducted that, you think? No, I don't think so," Trump said sarcastically. "You think they'd ever do a thing like that? I don't think so."
Campaigning in Virginia and Colorado on Monday, Trump sought to regain his footing after a damaging week by refocusing his attention on attacking Clinton.
The same candidate who spent days last week -- including one overnight tweet-storm-- blasting former Miss Universe Alicia Machado, on Monday complained that Clinton "focuses on small, petty things."
"We're going to talk borders. We're going to talk trade, jobs and refugees," Trump said of his message. "We're going to talk about crime and failing schools and how to turn our country around."
And Clinton, he said, will "do everything she can to distract from the issues."
Trump also showed he is increasingly aware and focused on early voting. He visited a volunteer call center that Trump's campaign said had already made 9,500 calls, and planned another volunteer visit later Monday night. Twice he reminded the voters in Loveland -- which is conducting its presidential election entirely by mail for the first time this year -- to mail in their ballots.
"All that stands between you and the country you want is Hillary Clinton's special interests," he said. "And all you have to do to beat those special interests is mail in those ballots and get out the vote."