I think what holds it back is that our space infrastructure sucks. To mine stuff - even really expensive stuff - and still turn a profit, it has to be sufficien

I think what holds it back is that our space infrastructure sucks. To mine stuff - even really expensive stuff - and still turn a profit, it has to be sufficiently cheap to do all the mundane things like get the equipment into space, repair the equipment when it breaks, get the product back to earth. All of that stuff is currently so eye-wateringly expensive that you could park a big pile of gold bullion on the moon and it would be safe from thieves because it would cost more to go and get it (per kg) than the gold is worth. Someone on Quora estimated that sample return from Mars costs about $1,000,000/kg using current tech[1], another estimate says $1,200,000/kg to the lunar surface[2]. No bulk material that I know of is that expensive. Platinum is $25,000/kg for example. Another issue is that if you mined a small amount of gold/platinum/whatever in space, you might make a profit per kg, but you wouldn't cover the huge fixed costs of operating a company in space. If you mine a very large amount (tens of thousands of tons), you would negatively impact the price of expensive materials, reducing your profit per kg (perhaps enough that you were making a slight loss per kg). Even news of a serious effort to mine stuff in space would dent the prices of what was going to be mined. I think this latter argument is sometimes overplayed though. At some price level the price would stabilise even with greater production because these materials are quite useful as well as being visually attractive and traditional stores of value. Better space infrastructure around earth could be as simple as SpaceX making reusable rockets work properly and reducing the cost per kg to get into low earth orbit. That could kickstart a lot of other developments like LEO (low earth orbit) space hotels, spinning space stations, in-orbit assembly. This would actually provide a nice market for asteroid mining - materials like water and metals could be put to use in space without coming back down to earth. We could have a thriving economy in LEO and MEO, supplied both from the surface and from trips to asteroids (some of which are not very far in delta-v terms from LEO) 1: https://www.quora.com/How-much-would-landing-and-returning-one-kilogram-of-payload-on-from-the-surface-of-Mars-cost https://www.quora.com/How-much-would-landing-and-returning-o... 2: https://space.stackexchange.com/questions/4720/what-is-the-marginal-cost-of-landing-on-the-moon https://space.stackexchange.com/questions/4720/what-is-the-m...