It Could Have Been A Brilliant Career by Belle & Sebastian delves into the themes of lost potential and unfulfilled dreams. It tells the story of an individual who, despite having the potential for a successful career, finds themselves stagnated and dealing with regret. Key themes of societal expectations, personal failures, and the harsh reality of life's unpredictability are explored throughout the song. Poignant moments include reflections on what might have been if different choices had been made and the lingering sense of 'what if' that haunts the protagonist, illustrating a bittersweet lament for a life that could have been significantly different.