Zillow lost money because they weren't willing to lose money
Good riddance. If large-scale house flipping took off, we might actually end up in a scenario where housing was treated as a speculative asset, with empty houses getting flipped between investors looking to make a quick buck, further lowering the supply of actual places to live (because housing units remain empty while being flipped), driving up the cost for families who just want a place to live. Oh wait...