> b) People are too optimistic about their future behaviour.

I read about a focus group once where a company was asking consumers about different color tea kettles. They had tea kettles in a dozen colors and asked people which one they would purchase. The responses were split fairly evenly among all the different colors. At the end of the day, the people who participated in the focus group were allowed to take home one of the tea kettles for free. Almost all of them chose white or black.