There’s a lot we’d be willing to do in space already, if the launch cost wasn’t so godawful. If a billion dollars got you ten science missions instead of one, that billion would be much more likely to get budgeted. What would the market be to get between North America and Europe to the Pacific Rim in an hour? I don’t know but I presume it’s greater than zero. If manned or telerobotic servicing was affordable, how big would communication relays be in geosynchronous orbit? We’d presumably be willing to spend at least as much on a lunar base as we do on keeping people in Antarctica. And there’s an “if you build it, they will come” factor: the more that’s already in place, the further you can extend from that.
I agree that a “killer app” that would immediately make space profitable would be a godsend, but even absent that we could be doing more of what we already do, and better.