It's not 100% retail investors, and whoever owns it today surely wants money. I don't know Uber's actual finances, but as long as you make enough money every month to cover last month's bills, you don't need to make a profit.

There are a lot of games that can be played with money to keep a company unprofitable but alive and healthy for a while. Look at amazon, a famously "unprofitable" company for almost 2 decades.