Michael D'Antonio is author of the book, "Never Enough: Donald Trump and the Pursuit of Success " (St. Martin's Press). The opinions expressed in this commentary are his.

(CNN) By now everyone knows that Donald Trump is an awful boss. The record-setting level of departures f rom his administration's top ranks proves this truth. Now it's starting to seem like he's also a terrible friend to those who would be his allies.

The right-wing rabble-rouser Ann Coulter recently declared at a talk at Columbia University that the President was a "shallow, lazy ignoramus" and that she's now a former Trumper. "If he doesn't have us anymore, that's what he should be worried about," Coulter later told The New York Times. "He's not giving us what he promised at every campaign stop."

Coulter's defection is significant because she was an early Trump supporter and has long been a leading voice on the fringe where the President's most ardent followers reside. She stuck with him through the scandalous claims of porn models and the chaos at the White House. But now she's fed up with his incompetence and feels betrayed -- principally on his failure to build the wall.

The most noteworthy aspect of Coulter's comments has been the sense of exasperation behind it. Other True Trumpers have expressed the same feeling. Tucker Carlson of Fox News, to name one, said the President's waffling on immigration issues left him wondering "what was the point of running for president?"

Carlson is a rabid partisan, but he's not a blind one. What he and Coulter both seem to recognize is that the man who ran for president on the basis of slogans and false claims really had no firm idea about how he was going to advance what little agenda he claimed.

Trump sold himself mainly on his status as an outsider who was going to "drain the swamp" and an anti-immigrant crusader who was going to deport millions of undocumented immigrants and build a wall the length of the southern border.

A sense of betrayal was expressed by some Republicans in Congress after the President appeared to resist a deficit-exploding budget but then signed it (sans funding for his wall). The same thing happened when he expressed interest in gun control after the school shooting in Parkland, Florida. In that case, longtime conservative firebrand and Trump supporter Grover Norquist took to Fox News to complain.

What Coulter, Carlson, Norquist and no doubt others are experiencing are the deficiencies Trump long exhibited as a businessman. After his renovation of a hotel at Grand Central Terminal and success with Trump Tower, in the late 1970s, Trump failed at operating a string of complex businesses -- an airline, various casinos, the Plaza Hotel in New York -- because he just wasn't a very good executive.

His fortunes improved as he focused on licensing his name to others, and acting as their promoters, and then found his true calling as a reality TV star, which is about as far from a leadership position as a person can get.

Having sold himself first to conservative dreamers like Coulter and Carlson, then to the GOP, and finally a minority of those who voted in the 2016 presidential race, Trump found himself in the White House thanks to the peculiar workings of the Electoral College. Because he had never developed an actual set of detailed policy ideas or, for that matter, a political philosophy, the promoter who became President attempted to bluff his way along.

The bluff began as Trump said he was going to hire the best people, and then installed in his administration a cast of characters that was filled with lesser lights. Michael Flynn, the general known for his poor judgment, was the first to depart in a cloud of his own deceptions. The subsequent flameouts -- Sean Spicer, Reince Priebus, Steve Bannon, Anthony Scaramucci, Sebastian Gorka, etc. -- comprise a murderers' row of egotism, incompetence and cluelessness.

There was also a cohort of those who could do their jobs but whom Trump couldn't tolerate, like FBI Director James Comey and Secretary of State Rex Tillerson. The proof that the boss doesn't know what he's doing is incontestable.

Were the President simply bad at hiring and managing people, he might have been able to satisfy his supporters by somehow delivering on his core agenda. Here the rest of his deficiencies come into play. Always an ethically challenged swamp creature himself, with his bankruptcies, infidelities and shady businesses , Trump should never have been expected to hire people with a keen concern for propriety.

Even if he intended to make good on promises, his poor choices of confederates has translated over and over into scandal and ethics investigations that distract from and derail his agenda.

The President has no true north to guide him as a leader. His astounding record of lies, including thousands demonstrated by fact-checkers, make it impossible for him to establish the trust necessary to conduct politics at any level, with friend or foe -- making it hard for even Trump's natural allies to maintain their confidence in him.

The tariffs the President has been brandishing provide a perfect example of how Trump makes himself hard to trust -- and an unreliable advocate for the policies that helped get him elected. When he first announced tariffs on steel and aluminum, some workers who considered Trump their champion were cheered. Then he began exempting countries that accounted for large portions of American imports, and the policy became almost neutralized.

After that flip-flop, Trump betrayed his supposed friend, China's President Xi, and went after Chinese exports to the United States. He even suggested that should a trade war develop, our side would win. With China retaliating, the Wall Streeters who had considered Trump a friend became wracked with anxiety. As stock averages roller-coastered, and the gains he claimed were proof of his success were threatened, Trump backed off.

From Xi to Wall Street to steelworkers and voters, Trump is treating many of his friends the way he treated the investors who bought the securities that collapsed when he went bankrupt. It's all good until the winds change and an ally has served his or her purpose.

It's only natural that Trump, an opportunist who sees everything in transactional terms, makes for an untrustworthy ally. He once told me that with billions of people on Earth, he's not worried about alienating anyone. With a friend like him, Trumpers are bound to be disappointed.