The nature of riska diver descends into an underwater cave, a scientist researches a dangerous, and an entrepreneur invests in a new business.Each time we try something new, we take a risk.Sometimes, like the diver or the businessman, we take big risks, usually for obvious reasons-for fame, for money, or to save lives.Most people will take some risk to achieve one of these goals.But as the danger increases, the number of people willing to go forward decreases.Only extreme risk-takers continue on.The question is: What exactly drives these people to go on when others would stop?