Pie-in-the-sky refers to being excessively optimistic about something that is unlikely to happen. The opposite of this would be to have a grounded and realistic approach towards a situation. Synonyms for grounded include sensible, realistic, pragmatic, and down-to-earth. The phrase "down-to-earth" refers to practical ideas and a realistic perspective. Antonyms for more pie-in-the-sky would thus include terms like pessimistic, cynical, negative, doubtful, and realistic. These antonyms describe a mindset that is cautious and skeptical about unrealistically optimistic propositions or ideas. It is important to strike a balance between being optimistic and realistic to achieve success in any endeavor.