He heard what no man survived hearing. Roped to the mast while his crew rowed deaf through the song that promised everything. The perfect metaphor for every temptation you've ever resisted.
The Sirens didn't promise pleasure — they promised knowledge. "We know all things," they sang. That's what made them irresistible. Odysseus, brilliant and curious, couldn't bear not to hear them. So he had himself bound and his crew sealed their ears with wax. He heard the song. He survived. Most people never figure out that the rope is the point.