They both have the same problem of needing large margins for being a middle man. Good ones no doubt, that provide good services for buyers and sellers, but they

They both have the same problem of needing large margins for being a middle man. Good ones no doubt, that provide good services for buyers and sellers, but they're still middle men. The kind of technology and services they offer seem pretty vulnerable to competition and becoming increasingly commoditized. Whereas the cost of providing a house/car and person to service it is not coming down. So the idea they can just keep extracting billions of dollars per year out of this (and massively growing that revenue to cover their vast operating costs) seems optimistic to me.