The phrase "making a killing" often refers to earning a great deal of money quickly and easily. Antonyms for this phrase could include "losing money," "struggling financially," or "earning a modest income." These antonyms suggest a lack of success or even failure in one's financial endeavors. Other antonyms could include "suffering losses," "breaking even," or "earning a steady but unremarkable income." In contrast to "making a killing," these antonyms paint a picture of a more challenging financial situation, where success may be more elusive and maintaining stability is the ultimate goal.