The phrase "are in habit of" refers to a common practice or behavior that an individual or group frequently engages in. Its antonym would be "are not in the habit of," which suggests that the individual or group does not regularly engage in a particular behavior. Another antonym could be "actively avoid," indicating a conscious effort to refrain from engaging in a particular action. Additionally, "rarely" or "infrequently" could be used as antonyms to describe the frequency of the behavior. Overall, the term "are in habit of" implies a degree of regularity and habituation, while its antonyms suggest a lack of regularity or avoidance of the behavior.