Had OPEC defended price as opposed to share they may have seen production fall by 5 M bpd and a price close to $100 maintained. The current course of defending 36 M bpd may take the oil price down to $20.
32 M bpd @ $100 is worth $1168 billion per year
36 M bpd @ $20 is worth $263 billion per year
The difference of $905 billion per year could make this one of the costliest blunders of all time.