守株待兔 (shǒu zhū dài tù)

Literally: Guarding the stump, waiting for a hare

Example: “上次中了奖，他就天天买彩票守株待兔。” — He won once and now buys a ticket every day, as if lightning struck twice.

English equivalent: Lightning never strikes twice

Origin: From the Han Feizi, chapter Five Vermin (3rd century BC): a farmer of Song saw a hare run into a tree stump and break its neck. He dropped his plow and waited by the stump for another hare, which never came, and became the laughingstock of the state. Han Feizi used it against rulers who cling to the methods of the past.