The significance of core subjects in graduation for UPSC aspirants lies in the foundational knowledge they provide. Subjects like Political Science, Economics, and Public Administration are often beneficial for understanding the nuances of the civil services. Graduates can leverage their academic background to tackle related questions efficiently in the examination. Moreover, familiarity with core subjects helps in building critical analysis and reasoning skills, which are crucial for all stages of the UPSC exam, including the Written Exam, Interview, and personality test.