Antonyms for the expression "being mad for" could include "disinterested," "unconcerned," "apathetic," and "indifferent." These words describe a lack of emotional investment in something or someone, indicating a sense of detachment or ambivalence. Being disinterested implies a lack of interest altogether, while being unconcerned suggests a lack of personal investment in the matter. Apathetic means lacking in feeling, interest, or concern, while indifferent implies a lack of preference or bias. All of these antonyms convey a sense of emotional detachment or lack of investment, which can be useful for describing situations where someone doesn't care very strongly about something.