The antonyms for the phrase "are a client" would include "are not a client," "are a non-customer," "are an outsider," "are not a member," and "are not affiliated." These antonyms suggest a lack of involvement or connection with a particular business, organization, or institution. They imply that the individual is not receiving any services or benefits from the entity in question. This lack of relationship can have various implications, including a lack of access to resources or information, lack of influence or control, or a feeling of exclusion or marginalization. In contrast, being a client implies a certain level of engagement, participation, and investment in a particular enterprise.