The phrase "sticks it out" implies perseverance, commitment, and resilience. However, its antonyms suggest the opposite traits, such as giving up, quitting, or abandoning a situation or a person. Some appropriate antonyms for "sticks it out" could be "gives up," "walks away," "quits," "reneges," "abandons," "disengages," or "runs away." The opposite of perseverance might also suggest reluctance or hesitance, suggesting someone that avoids or passes up on opportunities or challenges. Using antonyms can be useful to explore the various aspects or nuances of a concept and provide more clarity to one's writing or thinking.