Perhaps the best motivation for going to Mars is political. It is obvious that no single nation currently has either the will or the resources to do it alone, but a consortium of nations and space agencies could achieve it within 20 years.
“I'm learning to hunt with rifles, because if you think about it, hunting gets you the healthiest meat - organic, free-range food. It's a totally yuppie spin on what I thought was kind of a redneck occupation.”