I see this as more a situation (all too common, unfortunately) of biting off more than one can chew. It wasn't just about furnace expenses and yields, if I understand correctly, but of them taking on something they were incapable of pulling off with $$$ in their eyes. I've seen this out in the business world way too often... you even hear expressed in a 'take the job, then figure out how to do it' kind of way.
So, IMO, the story goes more like... potential sapphire produce courts and BSs Apple into picking them as a supplier, then can't pull the job off. Apple then dumps them, and they go under because their debts are way too high to possibly survive.