I didn't say that, but maybe it should be a combination of both. Which is why some cities are partnering with Uber/Lyft to do the last mile part (to the home), but using public transit for the bulk of it.
I do think you really have to question an economic model where Uber/Lyft have clobbered cabs using an unsustainable VC-funded model that will eventually run out and substantially increase cost to the end-user.
I think they're likely profitable in the cities where they've achieved scale. Specifically, I suspect that Uber (and Uber drivers) in the Boston/Cambridge market (where I live) are making a net profit overall.
Drivers who drive full time can afford to pay for the car expenses (variable and fixed). Drivers who drive part time are able to cover the variable costs (and they already had their fixed costs anyway). Uber is probably not losing money in Boston. If all three of those things are true, Uber is sustainable in Boston.
I do think you really have to question an economic model where Uber/Lyft have clobbered cabs using an unsustainable VC-funded model that will eventually run out and substantially increase cost to the end-user.