Several options apply:
A) He is a strong warrior and courageous leader. Odysseus never explicitly said his men was the reason for wanting to hear the sirens' song. However, since no one had ever heard the sirens before and lived to tell the tale of it, it could be inferred that the idea of doing something that no one else had ever done is likely very appealing to him.
C) He takes a long journey. His journey from Circe's island of Aeaea, where one of the main obstacles are the Sirens.
D) He has a group of followers. Along with whom he survived the sirens, as well as Scylla and Charibdys.
E) He engages in combat on his own. Odysseus ordered his men to seal their ears with wax, in order to protect them from the sirens' singing. In this way, Odysseous alone was the only one who hear the sirens' song.
