In my personal opinion Airbus needed the A380 to break Boeing's cash cow. The 747 was basically a running money tap at the time the A380 was conceived, and in order to level the playing field, Airbus needed to kill that cow. It's one of the weird strokes of economics where the company has to act against its own short-term interests, in order to create a long-term advantage (or rather, prevent a long-term disadvantage…
https://en.wikipedia.org/wiki/List_of_busiest_passenger_air_...