http://thespacereporter.com/2015/05/neil-de-grasse-tyson-advocates-militarized-space-race-mars/ That's the only way that enough money could be made available for such a project all at once -- and that the mission would involve sending people to Mars to settle and thrive rather than to die. Furthermore, as was true of the build-up to the Apollo missions, the economy would boom gloriously, and for once we might have an economic surplus. Go Neil! :-)
And while the idea of an internationally cooperative Mars mission is nice, it has to entail *cooperation* -- which the Great Nations of the world aren't very good on. Putin's Russia cooperate with America? China cooperative with India? Pakistan cooperative with India -- or Israel? You have GOT to be KIDDING me! And somebody needs to do this NOW, while we still can -- and why not us? We have all that data from our Apollo and Mars missions under our belt, so why not put it to use?