When you have a shit ton of eye balls, you have a money printing machine: "Ads". Just plaster them in the face of users. Now with machine learning and average user expecting little privacy, you can really target the ads and customize it per person.
It's amazing Wikipedia hasn't gone in the path of ads. I'm grateful for that.
If uber's self driving car gizmo works out, which there is a good chance. They can make zero profit on rides and make them $1/10 mile trip. Make the cream off in car entertainment and services.
They can have average person buy the car and rent it out to Uber network. Airbnb already loans money to home owners to renovate their houses.