complacent
kum-PLAY-suntadjMeaning so pleased with oneself that one stops watching for danger or trying to improve
Memory hook too COMfy in his PLACE. The shepherd gets so comfy in his place that he naps while the sheep wander off; too pleased with himself to keep watch, he is complacent.
After ten wins in a row, the team grew complacent and skipped practice.
In context Because the bakery had no rivals for years, its owners grew complacent; when a new shop opened with fresher bread, they lost half their customers in a month.
Similar smug, self-satisfied, overconfident
Opposite vigilant, alert, watchful
From Latin complacere, “to please greatly”: com- (thoroughly) + placere (to please).