Boeing has built and sold over 1,500 747s [1]. It first flew in 1969 and is now being end of lifed. It has been obscenely profitable over its lifetime. The A380 first flew in 2005 [2]. It has been a commercial disaster.
The 747 was a great plane for 1969. Airbus built the finest horse-drawn carriage just as the Model T came out.
> constrained slots at major airports serving the major routes
Between 30 and 40% of passengers departing from JFK or Newark will go on to a connection [3]. Consider what happens when they start flying directly to their destinations.
[1] https://en.wikipedia.org/wiki/Boeing_747
[2] https://en.wikipedia.org/wiki/Airbus_A380
[3] https://www.panynj.gov/airports/pdf-traffic/ATR_2015.pdf