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You criticize the optimists for so-called magical thinking and a "If you build it, It will come" attitude, but isn't that what's worked so far?
The internet (and personal computers in general) was mostly built by pioneering engineers/hobbyists/geeks who didn't have any kind of greater plan or grand design. They just thought it would be cool if computers could talk to each other, and they were smart enough to realize that packet-switching was the best way to do that.
Twenty, fifteen, hell, even ten years ago nobody could really have predicted what the internet would look like today. I remember reading an article (I wish I could find it now) back around 1996 predicting that the internet would fall victim to its own labyrinthine complexity, that one by one the search engines would sputter and die. Other articles predicted that there would be nobody willing to produce content for this new network. That the media giants would ignore it because it didn't fit their business model (ok, that part sort of has happened). But we've seen instead the rise of the indivdual as content-producer.
In light of everything that's happened, you don't think it makes sense to keep building and see what happens?