自满 (zì mǎn): complacent; self-satisfied

He became complacent because of a little achievement and stopped studying hard.

Complacent people often fail to see their own shortcomings and eventually fall behind others.

Even if you got a full score this time, don't be complacent, because learning has no end.

Arrogance and complacency will hinder your progress; only humility and caution can take you further.

We shouldn't become complacent because of one success, but should continue to work hard.