Vastly cheaper average cost for resources that can be mined in space might open up opportunities for economically valuable things that we currently won’t do on account of the Earth cost of those resources. To use your glass/lake metaphor, if all we have available for water is a dozen glasses per day per person, we probably won’t have much of a swimming pool or sprinkler system industry. If we find ways to pipe water from the lake, we might see much more demand for large volumes of water.
Vastly cheaper average cost for resources that can be mined in space might open up opportunities for economically valuable things that we currently won’t do on account of the Earth cost of those resources. To use your glass/lake metaphor, if all we have available for water is a dozen glasses per day per person, we probably won’t have much of a swimming pool or sprinkler system industry. If we find ways to pipe water from the lake, we might see much more demand for large volumes of water.