The phrase "left to luck" implies leaving things to chance, without any effort or plan. Antonyms for this phrase can include being proactive, taking control, and making calculated decisions based on information and analysis. Strategic planning, taking action, and being prepared are all opposite concepts to "left to luck." Additionally, being intentional, purposeful, and deliberate can be antonyms to "left to luck." These antonyms highlight the importance of being proactive and responsible in achieving desired outcomes, rather than relying on chance or luck to determine results.