Divine justice operates in ways that are not always visible to the human eye. Often, it seems that those who do wrong find great success while those who do good endure suffering. Yet, a deeper look reveals a profound balance of reward and punishment, built on a simple but powerful logical deduction [מצודת ציון, ביאור שטיינזלץ].
The primary approach among commentators focuses on the idea of exact accountability. Since no human being is entirely perfect, God addresses the few mistakes of the righteous by punishing them while they are still alive in this world [רש״י, מצודת דוד, ביאור שטיינזלץ, אמרי דעת]. There is a deep spiritual logic behind this method. By cleansing good people of their wrongdoings in this temporary world, where suffering is brief and minor compared to eternity, God ensures they can receive their complete and perfect reward in the World to Come [מלבי״ם, עמנואל הרומי].
This careful accounting establishes a clear rule for those who do evil. If God is so strict with those who strive to do His will, He will certainly bring judgment upon those who intentionally violate it [אלשיך]. As a result, wrongdoers have no reason to feel secure in their temporary achievements. Their ultimate punishment is guaranteed, whether it arrives during their lifetime or after their death [רש״י, מצודת דוד]. In fact, the worldly success they currently enjoy is merely the payment for the few good deeds they happened to perform. God rewards them now so that in the World to Come, they will face their full punishment without any remaining merits to protect them [עמנואל הרומי, מלבי״ם].
In contrast, another perspective views the earthly repayment of the righteous not as punishment, but as reward and protection. According to this view, good people are granted peace and security in this world. Even if they occasionally stumble, God watches over them and saves them from harm because the vast majority of their actions are good [רלב״ג]. Following this same pattern, just as the righteous see the fruits of their good choices during their lifetime, those who do evil will also face the consequences of their bad actions and be punished before they die [אבן עזרא].