I think anyone expecting space to yield exploitable resources at a feasible cost isn't really thinking this through and/or isn't being real about how big and empty it is.
Can you elaborate?
There is no substance that can be practically transported to earth from space at a cost that would justify the transport costs.
Are you talking about the current transport costs or theoretical optimal transport costs?
What do you think is the biggest part of the transport costs and why in your opinion can it not be reduced?