The phrase "반성을 왜 해 나 돈 냈지" can be understood in the context of the Korean word "반성." 반성 (反省) means self-reflection or introspection, where a person looks back on their actions, evaluates wrongdoings or shortcomings, and resolves to not repeat the same mistakes. It involves acknowledging faults with a degree of remorse and is often seen as a serious and sometimes painful process of personal growth and correction.

The phrase "반성을 왜 해 나 돈 냈지" literally translates to "Why should I do reflection? I paid money." This expression is likely used colloquially or figuratively, possibly implying a stance of not feeling the need for self- reflection or apology because the person already compensated or took care of some responsibility by paying money. It might be part of lyrics or street language where reflection or remorse is questioned because a transactional resolution (paying money) was made.

In summary, 반성 means a deep look back at oneself for mistakes and the determination to correct them, while the phrase questions the necessity of such reflection when compensation (money) has been given. This may reflect a more cynical or practical viewpoint in some social or cultural contexts.