Steve Siebold, author of “” spent nearly three decades interviewing millionaires around the world to find out what separates them from everyone else. It had little to do with money itself, he told Business Insider. It was about their mentality. “[The middle class] tells people to be happy with what they have,” he said. “And on the whole, most people are steeped in fear when it comes to money.” To read more, click here.