I tend to agree, though IANA planetary geologist. Folks tend to forget the value of things like nickel-iron, which could become one of the primary materials for constructing machines in space. It may well be that simple in-space products such as water and its constituents hydrogen and oxygen will become the largest economic activity for some time. Platinum is attractive in part because of the "Gold syndrome" - "OMG it's like GOLD! And it's just laying around out there, ins SPACE!" It does get people's attention. And I hope it's true - the entire space development industry or community or whatever is going to change forever with the first "killer app".
Regardless of the fun, I expect that an entire branch of metallurgy and materials engineering will arise around the use of nickel-iron and other available materials. Where many materials processes on Earth are based on liquid-phase chemistry, I expect that space materials processing will be much more based on solar (thermal and electric) powered vapor-phase methods, with additive manufacturing for actual components. Earth has some advantages - gravity, atmosphere, large amounts of water for solvent chemistry and cooling, etc. Space has different advantages.
For those who aren't familiar, some of the best types of steel, and other iron alloys, are basically nickel + steel + other things - see Iron Nickel Alloy.) I am not sure of the abundance of Aluminum in asteroids, but it's quite possible that the abundance of nickel steel in space may actually result in space-built hardware being made of these steels and steel-like alloys. Steel is traditionally iron + carbon, but the actual amount of carbon is on the order of 0.02% to 2%. The definition 's not that simple, but suffice it to say that nickel-iron alloys are valuable resources in space, though unprofitable for shipment down to Earth.