I fail to grasp this line of thinking: because it hasn't been done yet, it will hardly be done next. It is as if a XIX century Londoner tells me "Well, maybe we can get to the Moon, but since nobody's done it, it's pretty unlikely". And yet, a centurysome later... It hasn't been done yet because we don't have the capability, much like XIX century Britain didn't have the capability to launch a rocket into space. Time goes on, and opportunities arise, and so far, humanity's been pretty grasping about them. We now have an almost-instantanious information exchange between any part of the world, food production system capable of feeding billions, we can travel at astonishing speeds all across the globe and build both deep underground and high above it. Keep your mind open about what hasn't been done yet.