Starling Jet: A jet airplane that takes off like a helicopter
It's difficult to invent new types of the aircrafts. But, it's more difficult to commercialize it.
If you invest money infinitively, you will be able to invent something. But, if you want to commercialize it, it must be competitive with current one in terms of cost, speed, service, and so on.
In this case, cost of manufacturing Starling Jet and fuel consumption of it per passenger would be compared with cost for runways, manufacturing cost of current aircrafts and fuel consumption of it per passenger.