I think the way to use these big ideas is not to try to identify a precise point in the future and then ask yourself how to get from here to there, like the popular image of a visionary. You’ll be better off if you operate like Columbus and just head in a general westerly direction. Don’t try to construct the future like a building, because your current blueprint is almost certainly mistaken. Start with something you know works, and when you expand, expand westward. The popular image of the visionary is someone with a clear view of the future, but empirically it may be better to have a blurry one.
Paul Graham, “Frighteningly Ambitious Startup Ideas,” March 2012, http://paulgraham.com/ambitious.html