"It's already there" shouldn't need explaining. No part of "my plan" relies on anything that isn't there, or it would indeed be unfeasible. Seqeunce, as much as understanding, is something you seem to demonstrate consistent issues with.
What makes you think I'm waiting for anything? I am as it happens, I'm lazy, poor, and there's a few projects stacked in front of this one. But there again I didn't pencil this in for starting until mid to late 2017 so I'm still ahead of schedule considering I've started amassing parts for this and have preliminary designs for subsystems already, and some other projects will make this easier. Your belief isn't in the list of required materials, so luckily shall not be inhibative in the slightest. As this doesn't ask anything of you, or Dr. Ashurbeyli, wherin does the "con" lie?
Such a deployment of mining machines would not delay by decades, but accelerate by millenia. It shouldn't even take two decades to expand mining facilites to the point where the megatonnes of mass required are deliverable in timeframes considerably shorter than months, as opposed to the three to five thousand years of lifting from the surface. Or thirteen thousand years to only consider technologies available for use now, as the SLS system isn't active. And you'll be waiting these decades anyway, in the five to ten thousand years you could feasibly be able to come up with the finances to buy the raw materials, let alone transform into usable parts or even components. But, I'm the unrealistical one.
It does not drain funds, as it's fabrication and operation is taken care of via other means, and should this be unable to be achievable the total operational cost of the initaive until it can see a viable return is vastly below what it would cost to buy an island, install infrastructure, make suitable for habitation, and keep operating for 24 months. Should you of done a feasibility study, you could start putting numbers up here to support my claims. Two years of a island for 200 people vs payback in factors that make numbers you can't undersand, and requires no further input from that point.
The reason we don't have current space based mining industries(a few firms are looking to be getting into this as it happens) is because no-one has commited to the initative. Such a thing ultimately would only feasibly remove concepts like profit so are not commonly persued by those heavily invested in this thinking. Currently, I'm not aware of any asteroids being mined, only sampled. This does not mean it cannot be done, it just means it's not being done yet. The largest headache I foresee here would be avoiding the fabrication of additional debris. It's likley resonance can be used to fracture into smaller lumps and minimising kinetic and thermal output in the process.
I get a few hundred billion from the costs involved with buying an island, and making it suitable for habitation. If you'd done a feasibility study on this you'd have things like prices of the raw materials, shipping to destination, construction and labour etc added in too. And this will easily surpass the cost of the island. The rest respresenting the operational costs over time, which will be a few billion per decade minimally more likely annually.
I've still yet to be highlighted of a valid flaw. Let alone a gigantic one. Again, this doesn't add time, it reduces it by millenia.