Sunk costs should always be ignored when an investor makes an investment decision based on a company projected cash flow going forward.
Investors in JBII today get all the benefits of 3 years worth of trial and error expenses, capital investments, R&D, etc without any of those expenses reoccuring. It makes no difference if it cost JBII $500 million, $50 million, $5 million, or 5 cents to get to this point.