Incredibly efficient, but if they're burning hydrocarbons to move, at scale they are incredibly damaging to earth's atmosphere, and to animals disrupted by engine and propeller noise.

International trade is wonderful, all this new tech we're drowning in is amazing, and- understand that every one of us will eventually die, hopefully passing on some positive influence to others along the way, and that it turns out opting for the new car, the big climate-controlled house, the weekly/monthly/annual/still-too-frequent long-distance flights/drives, the new pocket computer every few years, the fancy unnecessarily-powerful laptop, the hours spent on all the man-child hobbies because we haven't outgrown our childhood insecurities, all this is an incredible waste compared to the meaning derived from healthy relationships with people within walking distance, tending the land we get our food from.

Another version of the idea is still around:

https://en.wikipedia.org/wiki/Rotor_ship

> This gadget seems to have durable appeal to entrepreneurs and/or suckers.

Or most research and technological development requires years or generations of experimentation and failure before success. And every time, the creators and innovators are told they are wasting their time, suckers, look how many failures came before you, ...