What does Psalm 73:19 mean?

Asaph's revelation about the wicked (Psalm 73:17–18) included the fact that God's judgment of them will be sudden (Acts 12:23). They will be destroyed in a moment. Terror will hold them in a death grip. This is at least a partial answer to the bitterness (Psalm 73:21) and angst of his initial complaint (Psalm 73:2–3). It is frustrating to suffer while honoring God, only to see some who defy Him living what appear to be comfortable lives. And yet, not only does their sin put them at risk of disaster (Proverbs 9:13–18), it guarantees them an eternity of judgment (Hebrews 9:27).

Just as the wicked people of Asaph's day seemed stable and happy, so too did the later king of Babylon, Belshazzar. Just as his judgment came with sudden catastrophe, so will be the end of those who reject God and celebrate their own sin (Psalm 73:8–9).

Belshazzar arrogantly hosted an elaborate banquet for a thousand of his lords and drank wine in front of them (Daniel 5:1). He and all his guests committed blasphemy by drinking wine from the temple's vessels and by praising idols (Daniel 5:2–4). But suddenly God announced Belshazzar's judgment by a finger that wrote on the plaster of a wall. Belshazzar was so terrified by the mysterious writing that he was notably shaken (Daniel 5:6). He learned from the prophet Daniel that God found him lacking and his kingdom would fall to the Medes and Persians (Daniel 5:26–28). That night those enemies seized the kingdom and Belshazzar was killed (Daniel 5:30–31).