"In the absolutely crème de la crème properties, in most of those market areas, there really is a tight supply," explained Lewis Goodkin, a real estate consultant in Miami. Fewer expensive homes for sale means those who can afford them are willing to pay more to get them.
Some have coined the phrase, "the billionaires are chasing out the millionaires."
And there's another factor that can drive up prices for affluent buyers, something that might not play such a big role for a typical homeowner.
"Not only do people at the highest income levels have the ability to withstand and wait things out, they have their ego at stake," Corcoran said.
And in Manhattan, those egos can match the skyscrapers and the sky-high prices.
"There are bigger egos in New York than in most places in the U.S.," said Corcoran "And people like to make a statement and one sure way to make a statement, 'I'm rich, I'm accomplished, I'm top dog, and I got the money to prove it and now, I have the biggest castle to prove it.'"
That $70 million penthouse? It's still on the market. Offers welcome.