My beliefs are that it is an absolutely wonderful idea, probably a long way off. It requires a largish infrastructure for 2 discrete purposes: 1) setting up, and doing the mining and then transporting the product, takes a lot more in space than we have or are williing to buy for a while, and 2) it takes a largish infrastructure to be the consumer of the materials - I like the product to remain in space to further our presence. Shipped stuff to earth has to compete with resources gathered here, and it certainly is not sexy.

A major problem is getting the resources from where you get them to where you need them. Best solution for that is to mine them where you need them. Second best solution is to mine them where it is cheapest to move them from: asteroids and Luna both have advantages and disadvantages.

Clearly, materials used in space are a lot cheaper if obtained in space than if they are transported from earth. (assuming infrastructure)

All this is pretty obvious stuff. I didn't post (or even read the thread) because I don't have anything new to say on the subject.