Why? Its just simple human nature, the desire to b

Why? Its just simple human nature, the desire to build, achieve and make a significant impact. Think about all of the multi millionaires and billionaires who still head up their companies and are continually pressing forward and expanding them. They couldn't even have spent all the money they had already made 20 years ago if they had retired back then, yet they still press on today without giving it a second thought.