If there was a megacity capable of holding 10 billion people in extreme luxury how big would it have to be? If 8 billion people voluntarily contributed to the project how long would it take? How much effort would one being have to put in? Because I think as a species we need a goal. And our species is capable of building one hell of a home. Our goal should be to make it the best home we possibly could. With our combined efforts nothing is beyond our ability to engineer.  But build as a species we should. The natural-born citizens of Earth free and equal deserve a home capable of surviving many future generations to come.