I think the argument is that if you take the airline industry as whole (so not just airlines, but aircraft manufacturers, travel agencies, airports, all the concessions there, ...) it's still very profitable.

And if you add the value to the customers, then it's through the roof.

Maybe the reverse is more clear: if air travel didn't exist, it would have a huge economic impact; a clear proof of the value creation. Airlines just happen to capture essentially 0% of it.

That's a false dichotomy. If airlines didn't exist, we would have found some other way to move things. Maybe trains, which would have been the better future by far.

What timeline are you in that we skipped trains and went to airplanes instead? We went to planes because trains were slow, and have a problem going across large bodies of water.

The reasonably best examples of commuter trains are far superior to those of commuter airplanes as long as we are not talking about travel over or around significant bodies of water or long distances.

Trains carry much more weight, are more fuel efficient, are safer, generally experience fewer delays and cancelations, and door-to-door are faster for shorter trips (<450 miles).

Safety: since 1964, the Shinkansen has carried over 10 billion passengers without a single passenger fatality from a crash or derailment.

Speed: for trips < 450 miles, trains win because of security, ATC, taxiing, etc.

The majority of travel is not over water. It may be that trains' other advantages are preferable even for longer trips where a train would be slower.