Investing in a company that doesn't make a profit is a bet on the come, in the hope they might in the future. The vast majority of companies that don't make profits, fail and go out of business. We saw the same thing 20 years ago with the original dotcom boom. Lots of companies with lots of VC money felt the imperative was to "get big fast" and worry about profits later. Most failed.
We are seeing a repeat with the "unicorns" and "deca-corns". Lots of VC money that subsidizes money-losing operation in the hope they can generate hype and then IPO cashing out while greater fools buy the stock.
When autonomous vehicles come online at scale, you can bet that Uber or Lyft won't be the ones producing them. Perhaps they'll buy them, but most likely the fleets will owned by the car manufacturers and they'll enter into a contractual arrangement with Uber or Lyft. Unfortunately, the value Uber and Lyft bring to the table are the internet transactions that request a ride, dispatch a car.and then bill the rider. Like most internet transactions, the marginal cost is essentially zero and that is the share of the rider's fare that Uber and Lyft will be able to get.
The car manufacturers will be providing all the value in the ride and they'll be in a strong negotiating negotiating position to get 99% of the fare. If uber or Lyft balks, then the car manufacturer will set up their own ride-requesting app.
The best thing for Uber and Lyft is if the autonomous future is well into the future.