Rest on one’s laurels
Etymology
The laurel wreath was the ancient Greek and Roman emblem of victory, awarded at the Pythian Games and worn in Roman triumphs, so "laurels" became a synonym for honors won. To "rest on" them warns that yesterday’s garland does nothing for today’s contest. The phrase has carried this caution since the 19th century.
verb · /REST on wunz LOR-elz/
To rely complacently on past achievements instead of striving for new ones.
What it names
The trap of coasting — treating a former win as permanent standing rather than a perishable one.
Example
The studio rested on its laurels after one hit and released nothing memorable for a decade.
Related idea
To rest on one’s laurels is to coast on the past, while the red queen effect is the opposite pressure — running hard just to stay in place.