The big concerns are whether drivers will continue to accept the pay they are offered. In 2018 they spent $837 million on excess pay to get drivers to accept certain trips. Insurance costs are also high, a large portion of their revenue.
Assuming their chart is representative of an average booking, $1 in excess incentives corresponds to a $10 booking. If so, 15-20% of their bookings appear to produce no revenue and cost money through excess incentives. They must be doing this to stay ahead of their competitors and/or encourage people to use the app.
Once the gross revenue picture is done, you have the relatively fixed operating costs. They are spending a fortune on marketing and consumer incentives, as are their competitors.
Overall they lost a bunch of money but made up for it through selling off the Russia/SEA businesses for a few billion. They also marked up their investment in Didi (which I believe they spun off before). But that's a paper increase.
So, they could become leaner. They also may continue to grow their way out of the hole. They do make money on most transactions. But becoming operating-profitable is a matter of putting competitors out of business and increasing demand for rideshare generally. They also need to get people to pay for the currently unprofitable trips. (Personally, I wonder how often they are leaving revenue on the table with their incentives.)