Airbus's global market forecast from 2000 predicted that 1,235 "very large aircraft" would be delivered to customers between 2000 and 2019. But from January 2019, Airbus had received 313 fixed orders and delivered only 234 aircraft.  The company's high targets were quickly undermined by the arrival of more fuel-friendly offers such as Airbus's own A350 or Boeing 787 Dreamliner.
The smaller aircraft were lighter and could run more efficiently as the expectation of a steep rise in the passenger journey failed to materialize. It was also found that very few routes could operate the A380 at full capacity.
Timing seems to have been a problem. When the A380 hit the world's runways, a worldwide liberalization of air routes known as "Open Skies" was underway. This allowed airlines to reduce their flights and fly more regularly.
Added to that is the increase of ultra long distance flying. Airlines have asked both Boeing and Airbus to come up with aircraft that can haul passengers from one side of the world without stopping.