certainly agree that's usually the way to get huge. and even the "hyper-ambitious" companies we fund have to start with going after a very small market--in fact, their first products mostly sound like toys, and that's a feature not a bug.
it's a mistake to build a startup that looks like a huge government project. it's also a mistake to not think about how to be a huge company one day. in fact, i remember one of the first meetings i ever had with airbnb. i told them how i thought that this silly-seeming thing they were doing could one day change the way most people travel. i think it seemed crazy even to them at the time.
Apparently, yes. Economic historians today argue that, throughout the eighteenth and nineteenth century, Enlightment-era notions such as "useful knowledge" and the Baconian concern with the "big scale" societal impact of scientific and technological work played a crucial role in "re-focusing" Europe's intellectual capital, as Joel Mokyr puts it [1]. In the twentieth century, seminal institutions like the OSRD, Bell Labs or (the old) DARPA --which as you know were behind most of the "truly revolutionary" inventions of the century-- had quite explicit utilitarian, "hyper-ambitious" mandates in their charters as directives --see for instance the writings of Vannevar Bush [2]. The development of modern organic chemistry and pharmacology was also quite explicitly motivated by tackling big societal problems, with many X-prize style prestigious awards for novel syntheses of crucial interest. And even the development of the internal combustion engine automobile by Benz [3] was quite explicitly motivated by his obsession to make it reliable and practical enough to fully supersede horse carriages and liberate cities from the iniquities of manure, which at the time was as "big scale thinking" as it gets.
Once you expand your perspective beyond the common troupes and political biases of the past 20-30 years, things start looking a bit different.
[1] http://www.crei.cat/conferences/RandD_and_Innovation_in_the_...