"Uber's success has been based on two unsustainable tactics: subsidizing fares and exploiting drivers" Considering Uber loses a billion dollars a quarter, I think the only people that are being 'exploited' are investors. Investor money is going straight to drivers and riders.
Investors presumably know the risks involved. On the other hand, many drivers are inexperienced and do not know the full cost of driving for Uber (vehicle depreciation and increased liability).
Except for working stiffs who are going to end up with Uber stock stuffed in their retirement accounts by unscrupulous portfolio managers.