If you regret the present outcome, why did you act in such a way in the past? (Used to express regret or blame for a past action that led to an undesirable current situation)
他当初不听劝告，一意孤行，现在项目失败了才来后悔，真是既有今日，何必当初。
He didn't listen to advice and insisted on having his own way; now that the project has failed, he comes to regret it. It's truly a case of 'if you regret the present, why did you act that way in the past'.
Era:
Early Modern
Frequency:
Next Idiom