Tunnels are predictable and scalable. Keeping it narrow at first … and when technology advances we can go wider and wider. As an example: building 200m wide domes instead would be gambling in a way. It would hold back economy.
Smaller projects / modularity can help us to advance with literally tens of thousands of projects from day one. We can get away with not waiting for central infrastructure at all. We can start to connect parts immediately … like neurons. Adding connections later is quite easy.
I’m continuing with an absurd idea here. Why a flat apartment in Brooklyn or Shenzhen is better than our natural environment? What is real or natural? What is the habitat we really strive for? Maybe a Takashi Amano like aquascapes could be an inspiration. Bits of nature … nature trails in our case?
Within this interconnected neuron cave system is possible.
Waking up on a tropical beach … surfing the “Bahamas”. A downhill ride in the French Alps. Maybe the jungle in Borneo. A blizzard in Norway or wetland in the Netherlands. All within our reach. A short walk away. We do it already here on Earth. Think about the high Line in New York