What you are missing is the marginal production costs. I would guess that now that they are masked out, the chips cost $10 a piece and the USB boards with heatsink (for example) cost another $10. Current price is 2BTC. There is a huge decrease in price that can be made and still be profitable. As competitors come online only one thing will matter: who can source their chips and boards the fastest.
that's where having the facilities and experience of producing 300 TH rapidly actually counts for something.
Being located next to the production facilities doesn't hurt either.