“We will have so much winning if I get elected,” Donald Trump exclaimed this past September, “that you may get bored with winning.” The line worked so well, that he now repeats it at virtually every campaign stop.

It’s a bold claim, and an alluring one—who wouldn’t want a winner as president? For that matter, who wouldn’t want to elect “the greatest jobs president that God ever created,” as Trump has also predicted he’d be?

It sounds alluring, but is it actually the case that people who proclaim themselves so loudly and so often to be winners actually succeed the most?

My research into business leaders suggests they don’t. On the contrary, it suggests that such bombast is one of a slew of behaviors embraced by spectacularly unsuccessful business executives. Unfortunately, many of these habits are part and parcel of the Trump leadership playbook.

For my book Why Smart Executives Fail, I interviewed some 200 people at fifty companies to learn why some people in business didn’t merely lose, but lose big. I discovered an interesting pattern: Spectacularly unsuccessful people tend to display a number of behavior patterns in common.

One of the most common is a tendency to see themselves and their companies as dominating their industry, regardless of what is happening around them. For example the co-CEOs of Research in Motion, the maker of the Blackberry smartphone, failed to appreciate the rise of the iPhone, going so far as to laugh off Apple’s new product as a nonstarter because it didn’t have a “real” touch keyboard. As we’ve seen with Donald Trump, denigrating your competition is one of the best ways to see this syndrome in action. Like Trump, the RIM CEOs felt certain they would win, and it cost them big-time.

Spectacularly unsuccessful executives also tend to think that they have all the answers. To all the questions. CEO Wolfgang Schmitt drove Rubbermaid into a ditch during the 1990s. A former colleague remembered that under Schmitt, "the joke went, 'Wolf knows everything about everything.'” Not surprisingly, know-it-all executives suffer because they fail to consider other points of view that might have merit. In fact, no one is always right, yet spectacularly unsuccessful executives act as if they are. In this regard, Trump’s impression of his own judgment and intelligence is telling. As he tweeted in May 2013: “Sorry losers and haters, but my I.Q. is one of the highest – and you all know it! Please don't feel so stupid or insecure, it's not your fault.” In September 2015, he made a similar statement on The Tonight Show, telling host Jimmy Fallon, “I think apologizing’s a great thing, but you have to be wrong. I will absolutely apologize, sometime in the hopefully distant future, if I’m ever wrong.”

And then there’s a related behavior, the tendency to underestimate obstacles. Unsuccessful CEOs are so confident that they blithely wave away the challenges that might impede them from realizing their visions. When these challenges materialize, do they backtrack? No! They double-down and get in even deeper.

In announcing his run for president, Trump proclaimed that he would solve the immigration issue by building a wall on the Mexican border: “I would build a great wall, and nobody builds walls better than me, believe me, and I'll build them very inexpensively. I will build a great, great wall on our southern border. And I will have Mexico pay for that wall. Mark my words.” Yet by most estimates, the cost of fencing in all 2,000 miles of border would be expensive, perhaps as high as $25 billion. Trump has talked about building a wall, not a fence, which would push the cost even higher. As for Mexico footing the bill, a spokesman for Mexico’s president has scoffed at the idea, noting that it "reflects an enormous ignorance for what Mexico represents, and also the irresponsibility of the candidate who's saying it."

But hasn’t Trump actually been very successful – in fact, a billionaire? Leaving aside the four bankruptcies, mostly due to problems at his Atlantic City casinos, there’s no question that his net worth today is in the billions. While no one can predict with certainty whether his business empire will remain intact in the years to come, CEOs who embrace many of the unsuccessful habits, as Trump does, are particularly vulnerable to a downturn. It’s almost like there’s a geological fault line beneath the surface, ready to erupt when the pressure becomes too unbearable. In my research, triggers like a major business downturn, a huge acquisition, and a strong new competitor were all responsible for turning seemingly thriving companies, run by leaders living the failing habits, into disasters in record time. Stress points typically bring out the worst in spectacularly unsuccessful leaders; habits that didn’t foul them up in better times can become fatal.

What might trigger those fault lines under a President Trump? Where to begin? Anything from a global crisis for which he lacks both personal experience and the makeup to be schooled by experts who may well have a different take than that of the intuitive deal maker who insists that he’s the smartest guy in the room; to even new economic crises that can’t be resolved with bluster.

Other research I have conducted raises still more concerns. In writing my current book Superbosses, I turned the table and explored why some executives succeeded more fabulously than others. In particular, I spent ten years probing the secrets of leaders who not only amassed great wealth, but who developed a generation of leaders in their industries. Here again I managed to identify a number of behaviors that these leaders had in common, including the willingness to share the spotlight with subordinates, the willingness to work closely with protégés and learn from them, and the willingness to hang back and give subordinates room to make their own decisions.

Trump’s answer to a moderator’s question in the most recent Republican candidate debate in South Carolina was telling:

Question: Can you tell us of an instance where somebody has said, “Donald Trump, you’re wrong,” and you listened to them?

Answer: Well, I would say my wife tells me I’m wrong all the time. And I listen.

Question: About what?

Answer: Oh, let me just say – look, I am very open – I hired top people. I’ve had great success. I built a great, great company. I don’t need to do this.

Superbosses have big egos, but the one thing they still do is make room for other people – their opinions, their ideas, and their influence. That’s how great organizations stay great. Trump not only appears to have a different leadership mindset, he also seems oblivious to the risks that often come with unadulterated egos.

These are all questions that cry out for more considered analysis by the press and the electorate alike. There is little we’ve seen about candidate Trump to ease these legitimate concerns. Predicting leadership behavior on the basis of past leadership behavior is smart, but not foolproof. But at a minimum, Trump’s adherence to key habits of spectacularly unsuccessful executives should be a warning sign. Does this mean that a President Trump will necessarily fall prey to the same weaknesses that have brought down previously successful leaders like Ken Lay of Enron, Dennis Kozlowski of Tyco, and Martin Winterkorn of Volkswagen? No. But is this a big-time risk that warrants close attention? As Bernie Sanders might say, you better believe it.

Sydney Finkelstein is a professor of management and Director of the Leadership Center at the Tuck School of Business at Dartmouth College. His new book is Superbosses: How Exceptional Leaders Manage the Flow of Talent (Portfolio/Penguin, 2016).