Why do eagles live that long?

The premise of your question is not accurate. While eagles do have lifespans that are longer than average compared to many other bird species, their exact lifespan largely depends on the species of eagle and certain environmental factors. For instance, while some eagles may have an average lifespan of 20 to 30 years in the wild, certain species such as Steller's Sea Eagles have been known to live up to 40 years in captivity. Factors such as habitat quality, prey availability, predators, and climate may also affect their longevity. However, it's not correct to assume that all eagles live extraordinarily long lifespans.