Consider, eg,
>Uber on Tuesday posted a profit of $394 million during the second quarter, compared with a loss of $2.60 billion a year earlier
This really doesn't answer or refute any questions around their business model.
The final question is: what's the moat?
It's trivial to create these "automate contract labour" apps, and many now exist. It seems an industry designed to reach, at its height, tiny profit margins.
I suspect regulation is heading in the direction of making it easier for people to move their data between apps too -- if that happens, the "social-data" moats of these bizes will disappear.
They'll be left with IP that teens could compete with