It assumed that the market would not react or it assumed that the VCs would keep funneling cash to keep it going.
Uber's business "model" always was unsustainable and the IPO and subsequent drop is entirely realistic as people realize that.
Uber Eats and some airy-fairy driverless vehicle models will not sustain it.
Currently Uber does not fund its vehicles, how does it think that the capital cost of running a driverless taxi fleet in a city will somehow be cheaper than the current cost of driver+car?
Uber doesn't have the capital to actually replace its current business model with one that is capital intensive and it will be eaten alive by existing fleet logistics and car manufacturers. It has no distinct advantage when operating a driverless fleet than Fedex or UPS or the equivalent operators.