Ridesharing is growing year after year, so their top line is growing fast. Self driving cars would remove the biggest expense which is the human driver, so the expenses will drop a lot. Currently it costs $1.50 a mile with a human driver, and should get down to $0.50 without a driver. The lower costs will increase the profit, and way increase the volume of people using Uber.

You're still ignoring the fact that Uber is the middleman here. Uber won't be manufacturing their own vehicles so when self driving takes off why wouldn't a car manufacturer directly offer the same service as Uber? They could undercut Uber and still make a profit because Uber will never be able to buy vehicles for as low as they can manufacture them.

Yes the driver is a big cost factor but so is the vehicle. If you can eliminate the driver and produce the vehicle and parts you will be able to produce and repair cars at rates lower than anyone without the same manufacturing capability.

> the biggest expense which is the human driver, so the expenses will drop a lot

This only makes sense if Uber driver's net income is pure profit. Instead I hear they have a set of expenses - fuel, insurance, tires, maintenance as well as servicing payments on the car. Some of these Uber is likely to negotiate down, mainly insurance. But some (cleaning, maintenance, parking, car washes, tires) are currently externalised to the driver and will have to be assumed by the company.

This is even before we get into the details of who manufactures the cars and how Uber comes into the possession of the vehicle (lease? outright purchase? purchase backed by a loan? etc.)

Some people will ALWAYS want to have a driver.