Stephen Roach, a professor at Yale University, says U.S. markets are largely ignoring risks because it's human behavior to believe in the message of growth rather than the reality of political upheaval. Sam Zell, the chairman of Equity Group Investments, says immigration is core to what built the U.S. Also, BNP Paribas' Stewart Warther says U.S. equity markets are getting close to being fully priced. Finally, Vince Reinhart, the chief economist at Standish Mellon, says stronger growth will be coupled with tighter Fed monetary policy than previously thought.