In any ground-breaking scientific enterprise, from railways to airlines to space travel, the first process is to produce a workable theory, then invest large sums of money and effort to create a working prototype, then reap the social, scientific and financial benefits.
The descendants of the original investors in railways and airlines are (mostly) billionaires, but the benefits inherited by the world are far greater than such a trivial concern. Following the original massive investment by the USA and Russia to develop the theories and prototypes of German rocket scientists into manned journies to the moon, the world has benefited in countless ways, from communications satellites to heat-resistant panels to non-stick pans, and enabling the development of many other life-improving inventions.
It is possible that present theories such as the “space elevator”, which in effect would be a super-strong cable hung from geostationary orbit, could, with the huge investment required, become a working prototype. The principal argument against such research is the enormous cost. However, the cost of transporting people and raw materials into space or back to Earth by rockets will always remain uneconomic, both financially and eco-sustainably.
Once the space elevator is in place, it would function at little or no cost because in the same way that an ordinary elevator uses counterweights to raise people tens or hundreds of floors, so people and materials travelling one way on the space elevator would provide the energy to move others in the opposite direction. Once valuable resources from the solar system are arriving on Earth, at little further cost, the benefits in terms of energy balance, and developing industries from the new materials, would rapidly produce a situation best described by the phrase “ever-increasing returns”.