There’s levels of R&D required for many technologies where the question goes beyond could this be profitable to what are the risk vs reward that this specific project will succeed.
Until the oil shocks, and until “normal” planes became faster.
I happen to know a couple older and very wealthy people, and they say that even though Concorde was a lot of fun when it was a novelty, they now prefer to have a couple more hours flight and enjoy a 777 premium cabin rather than the cramped Concorde interior.
Anyway, the proof is in the pudding: if no one but national carriers ever bought and operated Concorde or Tu-144 at scale, it's not because of some Amish-like sentiment in the flight industry, but simply because that didn't make sense money-wise.
Were they? IIRC joint project by British and French national airlines, they expected to sell loads, hardly anyone wanted to buy the planes, the two airlines kept them flying out of government embarassment.
Same way we dont _allow_ eugenics.
The US company trying to bring supersonic back are not only focussed on the flight speed, but also the entire customer experience.
We are able to effectively regulate things like the operation of massive aircraft, eugenics, the dumping of toxic waste, or the refinement of nuclear material. But there are also plenty of things that we can't effectively regulate for purely practical reasons.
In particular, the problem with it was that it could not get to supersonic speeds over urban areas, which significantly limited routes where it made sense, and the range was not good enough to cover longer distances.