OK, so Donald Trump may be a loudmouth, but he’s still a really successful businessman — right?

I mean, the guy’s made billions of dollars in the private sector, so he must know what he’s doing — yes?

Hmmm.

Trump may look like a smart business guy on TV’s “The Apprentice.”

But try telling that to anyone who invested their hard-earned dough in his great business venture, Trump Hotels & Casino Resorts Inc.

It was 20 years ago this summer that “The Donald,” for the first and only time, let ordinary schmucks on Main Street become his business partners and put their money where his mouth was.

The property mogul and best-selling author of “The Art of the Deal” raised $140 million from the public in the IPO of Trump Hotels & Casino Resorts, which owned his business interests in Atlantic City and elsewhere. (To put that in context, that’s as much as the average American could earn if they worked for 6,020 years.)

“ When the dust finally cleared from the wreckage, in 2005, those who had backed Trump found they’d lost about 90 cents on the dollar. ”

What an opportunity it must have seemed.

After all, casinos are a license to print money. And Trump was a genius at wheeling, dealing and self-promotion. Sure, he’d gotten overextended in the early 1990s. But who hadn’t? And sure, the bankers had taken him to the woodshed. But he was older and wiser now. By the mid-1990s, the economy was starting to boom again, too.

How could it fail? What could possibly go wrong?

Oh, dear.

When the dust finally cleared from the wreckage, in 2005, those who had backed Trump found they’d lost about 90 cents on the dollar. That was when the creditors — again — had to step in and take charge, and force the company through a Chapter 11 bankruptcy.

Trump Hotels & Casino Resorts lost money every single year that Trump ran it as a public company. Net losses of $13 million in 1995 ballooned to $134 million by 1999, and $191 million in 2004. Not even his chosen accounting firm, Arthur Andersen (of Enron fame), could have hidden all the red ink. In total, from 1995 through 2004, the company booked total losses of $647 million.

Trump had complete control — both as the chairman and as the owner of a special class of stock that carried many more votes than those he sold to the public. He even gave the company his initials, DJT, as its stock ticker symbol.

Its debts mounted, the stock collapsed — and in the end, the creditors had had enough. The courts stepped in, the company had to go through a Chapter 11 bankruptcy reorganization, and The Donald ended up with a largely ceremonial role — sort of like the guy in the costume welcoming you to Caesar’s Palace. By April 2004, someone who had invested a notional $100 in the IPO was left with about $10.

And it wasn’t like you could blame wider troubles in the industry, the economy or the stock market. Over the same period, investors in competitor Harrah’s Entertainment more than doubled their money. Investors in luxury hotel, casino and resort companies like Starwood and MGM earned returns of more than 400%. Even the plain old stock market index more than doubled.

It is already well-known that Trump’s businesses have passed through Chapter 11 four times over the past 25 years. Creditors have lost billions along the way. But as most of this has involved complex debt arrangements between Trump, his various business entities and dozens of banks, the details can easily get lost in the shuffle. Trump himself says he has merely been “smart” to use the corporate laws — including the bankruptcy code — to his advantage.

But the stock market is a little different. The losses are very public and very easy to follow — and the losers are ordinary investors who bought the stock directly or through mutual funds. Even worse, many of those investors are voters, too.

All in all, it’s a lucky thing for Trump that the public is so easily distracted … and have such short memories.