Of course it is impossible for us to know the true cost, but idle instances should not be accounted for at full price: 1. Idle instances don't turn electricity

Of course it is impossible for us to know the true cost, but idle instances should not be accounted for at full price: 1. Idle instances don't turn electricity to heat so that reduces their operating cost. 2. Idle instances can be borrowed for training which means flexible training amortizes peak inference capacity.