What happened that caused Odysseus' men to disobey him when Odysseus warned his men to leave the cattle alone?

In a word, starvation.  First, Eurylochus demands they
stop at Thrinacia, where the cattle of the sun god graze.  After landing, for an entire
month the winds blow in such a fashion to prevent them from leaving.  Odysseus leaves
the men to pray to the gods and then "down on [his] eyes they poured a sweet, sound
sleep" (12.364).  While he is asleep, Eurylochus convinces the other men to kill some of
the sun god's cattle in other to not starve to death.  The whole episode is another
variation on the eating and obeying the gods motifs as well as another way in which
Homer celebrates the virtue of temperance.