I think coverage of the A380 often misses the point that at the time, Boeing's 747 simply had no competition, whereas all of Airbus's planes did. So Airbus pretty much had to create the A380 in order to protect its other lines from cross-subsidy by this unopposed cash-cow. And, also missing from almost all the coverage is the fact that this worked: if the A380 is struggling, the 747 is moribund or dead. Official back…
In the 1970s the 747 averaged 32 orders per year. In the 1980s it averaged 43 orders per year. It peaked in 1990, taking in 122 orders that year alone, but from 1992-2000 orders dropped to average 27 per year.
In 2000, Airbus approved spending €9.5B to build the A380.
In 2005, Boeing announced the 747-8 to better compete with the A380.
From 2000-2009, the 747 had 214 total orders. The A380 had 212. Between them that's 43 orders a year. The market did not grow, despite substantially better, more capable, more efficient, products.
From 2010-2017, the 747 has booked 27 orders, or 3 per year. The A380 has booked 115, or 15 per year. 18 orders per year combined is by far the smallest jumbo market since it started.
There is no doubt that Airbus hurt Boeing's profitability by building the A380. But estimates are that Airbus spent €20B-€30B developing it, most of which it will never recoup. And the bulk of Boeing's profitability is in small to medium sized jets. It mints money with the 777 and 737. It never needed the low volume 747 to "subsidize" them.
Losing tens of billions so your competitor can lose a few billion is not a smart strategy. Good business strategy is making profitable entries into your competitors most profitable niches, not hemorrhaging money in them. Airbus and Boeing were both told that point to point was the future. Boeing heeded that advice (helped by a ton of their own customer research), Airbus mostly ignored it, and the end result is that Airbus crippled themselves while Boeing is as successful as ever.
The argument about airport congestion was always a false one. Not only can and will (edit) new runways and airports be built, but the A380's massive separation requirements gives back much of it's slot efficiency benefits.