I bet humans could have done a lot better than -$881M, and it wouldn't have been very costly to employ them. How many homes did Zillow iBuy in total, 10-20k? If it takes 5 minutes to evaluate a house, that would be 100,000 minutes, which is ~50 people working full time for a week. Spending $100k on that could have saved 100s of millions, plus it might have generated better training data for the model.