Er, there still seems to be a misunderstanding about why the company which doubles in space fastest will win, which incentivizes them to do so:
Company A produces 10Mt of nickel each year, here on Earth, and can grow production at 10% annually. Company B mines a Near Earth Asteroid, and uses parachutes to land 100Mt of nickel at its destinations. The price of nickel plummets to 1/10th its original value! Well, that makes Company A irrelevant, because Company B stole their *market share*, and Company A is now too expensive to operate, so it goes out of business.
If you are the CEO, and you see these two trajectories ahead, do you want to be Company A, or Company B? Company B got where they were by doubling productive capacity quickly.
And, to the concept that "supply can only match existing demand." No, that is empirically false, and your repeated claims otherwise do not change that fact. It's called Jevon's Paradox - you're welcome to wikipedia it. Simply-put, when the price-per-unit-output of a commodity drops, then we increase demand by a *larger* multiple, even when that drop in price per unit output came as a result of efficiencies in resource-utilization. So, just like energy markets before and after coal, we *create* demand once prices drop. That will keep happening.
Finally, no, Earth does *not* need to be the final destination of all space resources, nor do people need to colonize space before space has its own circular economy. Each company in space, depending upon the resources they are able to capture, will specialize in various parts. All companies have vendors supplying parts - no company is wholly self-replicating. Those companies, operating in space, will be demanding materials from each other, in order to accelerate their own doubling. That space-circular economy will grow larger than the entire demand on Earth very quickly.
Your idea that "the timeline seems too optimistic" ignores the numbers on factory-system doubling-times: If I need 90,000,000 kg of equipment, just to output 1kg per second of stuff, then I'm *still* on-schedule to double in two years. There's no way around those numbers, and businesspeople are going to notice, whether *you* think I'm optimistic or not.
