We have all our eggs in this one basket called planet Earth that could easily suffer a global disaster, perhaps destroying the human race, but at the least setting us back centuries or longer. Also, sometime within this generation or the next, we will run out of oil, and sometime after that, we will run out of coal and gas. And, as argued in the anti-congestion argument, global overpopulation may cause humanity to devolve. We will even run out of nuclear fuel. But that's in the future, and the space agencies of the world are going to be exploiting the resources from space by then anyway, right?
Wrong. They don't have the time or resources to explore at even one tenth of the speed that is required if we are to start making use of the resources in space before something bad happens to the human race. What is needed is a directed movement from a large portion of our population to help the space agencies with more money and people to do the work required. Quite literally a planetary effort. Bearing that in mind, it must be said that this is an achievable goal, especially with a tool like the Space Colonization Wiki that allows us to have a truly global communication system that everybody can operate. So please, join in and help direct the next stage of human evolution.
One important way to evolve is by not justifying things, see Advice of ways to stop justifying, multiple stages of justification poisoning, brain, inheritance of acquired characteristics and self-organization on http://purescience.wikia.com.