Rappaport is currently marketing a Beverly Hills mansion once owned by publishing magnate William Randolph Hearst, a house with the highest asking price in the United States: $165 million.
"It may take a little while. We've already had a couple of offers. It's been on the market only for a very short period of time. There's a lot of interest -- a lot of people coming from all over the world and locally to see it," Rappaport said.
The mega-rich will continue to spend this kind of cash as long as real estate is viewed as profitable, according to Rappaport.
"I don't see any stop to it, because I think real estate is the most understandable asset to acquire," he said. "This is not like buying a position of a company that could be worthless in a couple of years. This is a piece of property, you can walk on it, you can feel it, you understand the location and the magnitude of the house, that's real value. That's why people perceive real estate as being the best long term investment."