What those 77% of people fail to realize is that we can no longer organize ourselves well enough to accomplish this sort of task. NASA, as an institution, long ago stopped being about technical successes and exploration. During my years working with NASA, I discovered that a NASA manager's career success is measured solely by the number of people they manage and the size of the budget they control. Not by how many successful missions they achieved, not by the technology breakthroughs they fostered, and not by any other rational measure beyond their org chart success.
So we have no government agency capable of focusing on such a complicated goal as landing humans on Mars. They immediately get distracted with project management issues and politics. If private industry were to try and undertake this effort, there would have to be some financial incentive for our largest private spacefaring corporations to try and cooperate, since none have the resources alone to achieve the goal within 20 years. And the only model they have for organizing themselves is NASA today. No one still working in the industry knows how NASA of the 1960's worked, and society has changed to the point that the technical people required for such an effort are no longer motivated to make the selfless sacrifices needed to achieve such a goal. All the good engineers left aerospace for the Dot.Com world in the '90s. Those remaining few are motivated by commercial and personal financial success, and that requires a much shorter planning and gratification cycle than 20 years.
Sorry, we won't be going to Mars. We're a bunch of greedy, self-absorbed, small-minded apes that have reached the pinnacle of our organizational skills at the bottom of our gravity well.