rest on one's laurels

Rely on one's past achievements, especially as a way of avoiding the work needed to advance one's status. For example, Now that Julian's in his eighties, he's decided to rest on his laurels and let some of the younger agents do the work . This term alludes to the crown of laurels awarded in ancient times for a spectacular achievement. [Late 1800s]

To stop participating because of satisfaction with past achievements. The ancient Greeks crowned their victorious athletes and poets with wreaths made from the laurel bush, as did the Romans to honor their triumphant generals. People who have in their own estimation been sufficiently successful and retire from whatever endeavor they were successful in are said to be resting on their laurels.