There are indeed many factors involved in the fall of Camelot, but selfishness would appear to be the most important. The Knights of the Round Table have sworn loyalty to their king, yet act in ways that betray that solemn oath, putting their selfish needs before their sacred duty. Lancelot, for example, sleeps with Guinevere, undermining his bond of trust with King Arthur. It is this flagrant breach of fealty to his master that leads directly to the fateful conflict between the two men. The transgressions of Lancelot and Guinevere don't simply constitute adultery; they are nothing less than high treason. They must have known, then, that their illicit affair would have serious repercussions, yet they carried on regardless, putting their base physical needs ahead of the kingdom's political stability.

Lancelot's betrayal of his king leads in turn to other members of the court behaving selfishly. Mordred and Agravaine betray Lancelot and Guinevere to Arthur, not out of selfless duty, but out of a desire for power and prestige. Ultimately, Mordred has his eye on Arthur's kingdom and sees the fall of Lancelot as an opportunity to advance his claim. Lancelot and Guinevere's tawdry affair may have set Camelot on the road to its ultimate fall, but it was arguably the self-serving exposure of that affair by Mordred and Agravaine that acted as a catalyst for the ensuing turmoil.