Exactly: if they double total revenue then NET revenue (after driver payouts) only grows to $1.4M

Sounds awesome but currently the net revenue was 700k which means they spent ~$1mm on other stuff besides driver payouts. Some of that will grow with the business (e.g. customer service, server hosting costs), some is fixed (e.g. you only need one CEO).

If they can grow the revenue without also growing expenses then they'll hit breakeven by ~doubling revenue, maybe more, maybe less.

Interestingly, i just checked their prices to JFK and they're about the same as Uber. So if they grow beyond breakeven, then they could undercut Uber's current prices...