This psalm forms a chiastic structure:
1a) Psa 52:1, The goodness of God endures continually;
1b) Psa 52:2, The tongue of the wicked devises destruction;
1c) Psa 52:3-4, The wicked loves evil, lying, devouring words, deceit;
1d) Psa 52:5, God shall uproot the wicked from the land of the living;
central axis) Psa 52:6, The righteous shall also see and fear;
2d) Psa 52:7, Here is the man who did not trust in God, but in riches and wickedness;
2c) Psa 52:8, David trusts in the mercy of God forever and ever;
2b) Psa 52:9a, God has destroyed the wicked;
2a) Psa 52:9b, I will wait on God’s name, for it is good.
One reason the LORD uproots the wicked from the land of the living, is so that the righteous will see it, and fear God. The fear of God is the beginning of wisdom, it is a good and healthy thing to fear God.
And, the goodness of God endures continually. God is good all the time, even in the Old Testament. Everything that proceeds from God is likewise good: but more proceeds from Him than mercy. Truth, Torah, and judgment of sin also proceeds from Him. Judgment of sin is an expression of goodness and mercy, because it relieves the victims of violence.