The cost of putting a single car and driver-for-hire on the streets is a handful of dollars, so it's easy to do many of them at a loss. The cost of putting a single instance of a new airplane design of this scale into the air with even a single paying passenger is in the range of billions if not tens-of-billions of dollars.
This is not even remotely comparable.
But just for comparison, Aérospatiale and BAC actually built a real supersonic plane (Concorde) and managed to fly and operate that plane for decades. It's hard to find much measurable impact on the world at all. What do you propose would be different here, given that the discussion is already presuming a world in which they haven't succeeded economically?
