Over time, that can backfire, Johnsen said.

"You may get a really wonderful deal the first time," she said. "But there will be a reputation that's formed. And people will be on their guard. There are no one-off negotiations because it's such a small world."

That's proving true in the diplomatic world as well. Trump has notched a few successes, like a new South Korean trade deal. But, for the most part, other countries have not bent to his will. Mexico hasn't paid for the border wall. Europeans have not cut their steel exports. And China shows no sign of abandoning its high-tech development strategy.

Hardball tactics may work in a one-off real estate deal but they don't foster long-term relationships. By pulling out of the Paris climate accord and slapping tariffs on the European Union, Trump may have jeopardized his chance of winning allies' help in revising the Iran nuclear deal.

"Those European allies, they're not sure anymore," said Leslie Mulligan, who trains negotiators for the consulting firm Watershed Associates. "That trust has been eroded a little bit in terms of those relationships that we have."

Mulligan said there's nothing wrong with setting ambitious goals for a negotiation, or what Trump calls "thinking big." But the person sitting across the table also has a say. Successful negotiators craft agreements in which everyone walks away a winner. They don't just assume they can dictate terms of the deal.

"I think instinctively he still thinks we're the biggest. We're the best. And we should be able to get what we want," Mulligan said.