Richard “Rick” Hough vividly remembers coming out of the subway and walking up Fifth Avenue to work. “It was the most perfect day,” he recalls. “September in New York is often gorgeous. Low humidity. Not a touch of cloud in the sky. I was a little later than usual and people on the street were all facing downtown. I was walking up but they were all looking down. I could see a black plume, but couldn’t quite tell it was the Twin Towers.”  Hough was in his early 30s, and working in a successful non-profit raising hundreds of millions to…