Establishing a self-supporting colony on Mars would change world history – it wouldn’t be just “world” history any more. A Mars colony would provide a life insurance policy against whatever catastrophes might occur on Earth. Our planet is littered with the bones of extinct species offering mute testimony that such catastrophes do occur. The real space race is whether we will colonise off Earth onto other worlds before money for the space programme runs out.
History shows that expensive projects such as the Egyptian pyramids or Chinese naval explorations are often abandoned after a while. The human space-flight programme is not very old, suggesting we should colonise soon, while we have the chance. Colonies are a great bargain and have the potential to found other colonies: the first words spoken on the moon were in English not because the UK sent astronauts to the moon but because England planted a colony