Elon Musk, who dreams big, believes he can create a Mars community of 80,000 during his lifetime. An excerpt from Discovery piece by Rob Coppinger about the proposed space colony:

“He also estimated that of the eight billion humans that will be living on Earth by the time the colony is possible, perhaps one in 100,000 would be prepared to go. That equates to potentially 80,000 migrants.

Musk figures the colony program — which he wants to be a collaboration between government and private enterprise — would end up costing about $36 billion. He arrived at that number by estimating that a colony that costs 0.25 percent or 0.5 percent of a nation’s gross domestic product (GDP) would be considered acceptable.

The United States’ GDP in 2010 was $14.5 trillion; 0.25 percent of $14.5 trillion is $36 billion. If all 80,000 colonists paid $500,000 per seat for their Mars trip, $40 billion would be raised.

‘Some money has to be spent on establishing a base on Mars. It’s about getting the basic fundamentals in place,’ Musk said. ‘That was true of the English colonies [in the Americas]; it took a significant expense to get things started. But once there are regular Mars flights, you can get the cost down to half a million dollars for someone to move to Mars. Then I think there are enough people who would buy that to have it be a reasonable business case.'”