Customers, who also use all 12 apps simultaneously, will be unable to get an Uber in a timely manner, open a different app, and the same driver who would otherwise have picked them up for Uber will pick them up for one of the twelve different competitors.
The driver gets paid, Uber doesn't get a cut, and a little bit of brand loyalty is lost as the customer is a little less likely to open Uber first the next time.
However, the cost to Uber is hard to predict - the strike is on the day of the IPO. If they can depress the share price at IPO by a few percent that potentially costs Uber far more than all the lost rides.
Edit: I suppose the entertaining thing about the gig economy is that it's possible to be "on strike" at employer A while working for employer B. Especially as there's no picket line here. (I think a few French anti-Uber strike/protests did have roadblock picket lines)
Utterly absurd assumption, they know exactly the cost and better than anyone else.
Taxis still exist, surge pricing really will struggle above that. Most uber rides aren't of necessity, many studies have shown they replace public transport.
That's really the basis of my comment. It's not an assumption, it's quite black and white.
It would also show how selfishness hurts you in the long term, and why unions are necessary to establish balance of power in negotiations.