> pyramid scheme that only works until you run out of undeveloped land.

The whole point of a pyramid scheme is they don't create value.

Developing the undeveloped is a productive contibution to the economy. Solving the housing crisis is a productive activity

> this is already done in the form of suburban sprawl

You have to create high-density housing, apartments, and local amenities. Pulling expensive underground rail tlinto a group of suburban homes is a waste

> You generate a bounded one off income

keep them and rent them out