The line comes from Illidan Stormrage, the antagonist of Warcraft III: The Frozen Throne from 2003, voiced with a distinctive demonic rasp. Blizzard reused it as his signature aggro quote in the Black Temple raid of World of Warcraft: The Burning Crusade in 2007, where millions of players heard it before wiping. Clips of the encounter spread on YouTube and forums, and the phrase became shorthand for doomed overconfidence. It endures because it fits any situation where someone ignores an obvious warning.