Elon has done back of the envelope calculations and believes that Mars colonization can be profitable at a cost of around a half-million per ticket, with a free return for anyone who decides they want out.<p>At that price point, moving to Mars is something you can fund by selling your house.  If enough people want to do it, he could make a <i>lot</i> of money that way.  In addition to going down in history.<p>If he is wrong, well, it is his money.  And every step along the way to building that capacity can be justified by ventures that are making money <i>now</i>.