For years, I've had a hankering for the portrait of Benjamin Franklin by Joseph Duplessis. Franklin is credited with so many inventions: the postal system, lightning rods, the constitution. He was a rock star before there was such a thing.
I'm sure that is a reason why young people occasionally bash up old people - because the ages don't mix any more.
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.