Donald Trump's golf resorts lose a lot of money. According to a bombshell New York Times report published last year, the 15 courses he owns around the world have lost over $315 million over the past 20 years. The interesting question is why does Trump hang on to so many money-losing enterprises?

Much about Trump's financial arrangements remains a mystery — partly because privately listed companies in the US can largely avoid public scrutiny — though investigations into whether Trump committed bank and tax fraud may reveal more.

No one's quite sure how much he's worth. No one's sure why the self-styled "king of debt" decided to plow up to $400 million into his two Scottish golf resorts. And no one's sure what his tax returns might turn up.

But because the United Kingdom has a registry of companies that requires them to publicly file accounts every year, we can look in detail at how much his two courses in Scotland lose every year and how much debt they've racked up. (Hint: It's a lot.)

So why do Trump and his sons, who ran his businesses while he was president, continue to run courses that lose so much money?

Read more: EXCLUSIVE: Documents reveal how Trump is spending taxpayer money on his postpresidential offices — from printer toner to Stephen Miller's salary

We spoke to leading experts, examined the financial data, and looked back at Trump's own words on the matter to find out why.

Insider contacted the Trump Organization for comment but did not receive a reply.

Trump has two golf resorts in Scotland. He opened the first, Trump International Golf Links, in Aberdeenshire in 2012 on a piece of land he had purchased six years before. The course has lost money every year since.

Company accounts for 2019 — which covered the period before COVID-19 wreaked havoc on many businesses — showed that Trump International Golf Club Scotland Limited, which owns the course, posted an annual loss of $1.5 million. The total debt on the resort is more than $60 million, the balance sheet showed.

The second course is Turnberry, the crown jewel of his global golf empire. He paid $60 million in 2014 for the storied resort, where Tom Watson famously scraped out a win over Jack Nicklaus at the 1977 Open Championship.

Trump claimed to have spent a further $150 million on its lavish refurbishment. Turnberry's parent company, Golf Recreation Scotland, posted a $3.25 million loss on revenue of $26 million in 2019 and owes nearly $160 million to its creditors, the balance sheet showed.

Such losses are not unprecedented in the industry. Running a golf resort profitably is hard to do, said Larry Hirsh, the president of Golf Property Analysts, which values and markets golf properties.

"Over the last 10 to 20 years, golf courses have had their challenges," Hirsh told Insider.

"It costs a lot to go play, and Trump has never been shy about pricing his properties. Certainly, golf has experienced over the last 15 or 20 years a decline in participation," he said.

However, he added that "it's certainly not the idea" for major golf courses to lose money. "I don't think it's normal," he said.

Trump said in a 2016 interview with Reuters that people looking at the massive losses at his golf resorts were missing the point.

He said his resorts were "not really golf investments" but real-estate "development deals."

"It's pretty simple," he said. "My golf holdings are really investments in thousands, many thousands of housing units and hotels. At some point the company will do them. Hopefully, I won't because I will be president, but we're in no rush to do them."

There's just one problem with those claims: Trump hasn't built a single residential property on any golf resort he owns in the past decade, in Europe or the United States, Reuters reported last year.

He secured provisional permission in 2008 to build about 1,500 luxury homes and a hotel on farmland surrounding the Aberdeenshire estate, in what the Trump Organization had billed as the "world's greatest golf course." The economic gains would outweigh the environmental impact of the building work, officials said. But neither the houses nor the hotel materialized.

In 2019, he secured approval for a reworked plan to build 500 homes, but construction hasn't started.

At Turnberry, Trump failed to secure permission to develop hundreds of houses on the adjoining land. He had boasted to Reuters that he "would have the right to build at least a thousand houses on Turnberry, if I wanted to." But Scottish planners had different ideas. In 2019, the local authority rejected plans to develop the land, The Scotsman reported.

The ruling said the development could "negatively affect" Turnberry's status as an iconic resort. It suggests that Trump's plan to build houses on his golf resorts may be unsound from a business perspective.

That brings us to the second theory: incompetence.

"Stupidity and grandiosity should never be overlooked as possible grounds for all of this," said Daniel Shaviro, the Wayne Perry Professor of Taxation at New York University Law School, who wrote about Trump's tax returns last year.

Trump's patchy business record is well documented. He demonstrated a genius for self-marketing and licensed his name to resorts and luxury developments all over the world, propelling him to the White House. But his businesses have also filed for bankruptcy six times, and he counts dozens of hugely expensive failures among his successful business ventures.

There were his Atlantic City casinos, which closed after racking up billions of dollars in debt. There was Trump University, which paid a $25 million settlement to former students in 2017 after New York's attorney general called it "fraudulent." And there was a short-lived airline called Trump Shuttle.

The accounts for Turnberry and Trump Links suggest they may be two further examples of poorly run businesses. A detailed analysis of Trump's two courses by Behind the Balance Sheet, a financial research consultancy, illustrated that profits had been consistently lower than at other established rivals in Scotland, including Loch Lomond Golf Club and Gleneagles, and that capital expenditure had consistently outstripped revenue growth at both resorts.

All in all, it's difficult to see how either business would ever generate a positive return on Trump's huge initial investment.

Companies House accounts showed that Golf Recreation Scotland, Turnberry's parent company, depends on an eye-watering amount of debt — around $160 million — owed to its parent company, the Donald J. Trump Revocable Trust, which is registered in New York.

Trump International Golf Club Scotland, which controls Trump's Aberdeenshire resort, owed Trump more than $55 million, and nearly $5 million to its parent company, DJT Holdings.

Their loans are unusual, however, because they are interest-free, negating the tax benefit of loaning money between companies owned by Trump, Mother Jones reported in November.

It's "a bit fishy," Shaviro said.

"Under US tax law, you can't really have an interest-free loan between related parties," he said.

"There would be a tendency to impute the market interest rate, or else they say it's really equity.

"So when separate tax entities are engaged in transactions, the idea is that it's got to be arm's length, it's got to reflect reality."

Shaviro said it wasn't clear there was any tax benefit to the way Trump had set up the loans.

"I don't see the obvious tax benefits here," he said. "Whether it's money-laundering or playing games with lenders, there is a pretty good guess something is going on, but I'm not sure exactly what it would be."

That brings us to the last theory.

A group of Scottish lawmakers led by the Green Party's Patrick Harvie this year called for an "unexplained wealth order" over Trump's finances. Their central question: Where did Trump get the money to pay for his resorts in the first place?

Harvie, a member of Scottish Parliament, said in February: "The purchases in Scotland were part of a very long spending spree, with his spokespeople claiming that he had vast sums of money sitting around and available for investment even though, at the same time, he was apparently being turned down for credit."

Trump, who once called himself the "king of debt," had spent his career building businesses on other people's borrowed money, even bragging about it on the campaign trail in 2016.

He began that spending spree in 2006, buying up more than $400 million worth of properties in cash over the next decade, The Washington Post reported in 2018. The first purchase was his Balmedie estate. The most expensive was Turnberry in 2014, even though it was losing money then, too. He purchased a course in Doonbeg, Ireland, in the same year, also using cash.

Harvie alluded to the closed-door congressional testimony in 2017 of Glenn Simpson, the head of Fusion GPS, the political-research agency that produced the so-called Steele dossier on links between Trump and Russia (one part of which a UK judge called "misleading").

Simpson told lawmakers that the firm's investigations had identified in the Trump Organization "patterns of buying and selling" real estate that "were suggestive of money laundering."

Later, he said that "because the Irish courses and the Scottish courses are under the UK," Fusion GPS was "able to get the financial statements."

"And they don't, on their face, show Russian involvement, but what they do show is enormous amounts of capital flowing into these projects from unknown sources and — or at least on paper it says it's from the Trump Organization, but it's hundreds of millions of dollars," Simpson said. "And these golf courses are just, you know, they're sinks. They don't actually make any money."

Trump's son Eric said last year that Harvie's claims had "no basis in fact" and called them "disgusting."

Scotland's government rejected the calls for an unexplained wealth order on the grounds that it was for the country's law officers, not politicians, to instigate such investigations. Nonetheless, these questions about how Trump paid for his golf resorts and why they keep losing so much money will only grow.