My impression is that the A380 was an impressively big plane (not that attractive, like a big flying beluga) but just too costly to operate and maintain.
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It’s efficient enough to be competitive.
The problem is airlines and passengers prefer point to point routes rather than going through a hub. The A380 is strictly meant to fly from one hub to another.
That is an even more fundamental question, as you sound read up on it (I have been a subscriber to Aviation Weekly for some time so I have been able to follow it)
There was a gamble about the future of profitable aviation, and Airbus I think hedged their bets with the A380 on that hub concept...and there was much speculation on which one was going to bear out.