They are taking cars that are not particularly desirable, selling them to their own leasing company at full retail, collecting 4 times as much money per month than any same person would pay, earning money on every mile driven, and... I'm not sure about this one, but I _think_ they reduce the pay of the drivers who do the leases (I know Lyft does this).
Then they are "selling" the cars at a loss. But are they selling the cars at a loss to the wholesale market at large? i.e. putting them up for auction at Manheim/etc.? I doubt that is happening. More likely they are selling them to yet another subsidiary or affiliated company.
You don't lease a 15K car to someone at $800/month and lose money.