The term "bigtime operators" refers to individuals or companies that are highly successful and influential in their respective industries. Antonyms for this phrase could include words such as "small-time", which refers to individuals or companies that are less successful and have less influence, or "amateur", which refers to someone who is inexperienced or lacks professionalism. Other antonyms for "bigtime operators" might include "mediocre", "ineffectual", or "undistinguished". These words all suggest a lack of excellence or superiority, making them the opposite of "bigtime operators". It is important to choose the right antonym, depending on the specific context in which the term is being used.