Amos has chastised the rich and powerful who take advantage of the poor. "The time is surely coming," the Lord God had told him, "when I will turn this extravagant display into a time of mourning."
Psalm 52 is the lectionary response to that passage.
The psalm addresses the powerful, "Why do you boast of the mischief you have done against the godly? God will see that you pay for what you have done."
And those who have been harmed but remained faithful to God will see the downfall of the mighty ones: "See, the one who would not take refuge in God, but trusted in abundant riches, and sought refuge in wealth!"
Rich sure seems good to us much of the time, but the Psalms remind us that being rich is not satisfactory as a total goal. For one thing, it doesn't last. For another, seeking that goal at the expense of all others results in our loss of everything important.
Rather, than trust money, this Psalm reminds us to trust in God forever and forever and to thank God--publicly.