What does Psalm 49:18 mean?
A rich man may consider himself blessed because he is wealthy and praised by others. That might be true—God can use material resources to encourage His people—but earthly wealth can never last beyond earthly life (Psalm 49:10, 16–17). Praise from other people is also not wrong when it's truthful and godly (Proverbs 3:35; Romans 13:7). Yet the praise of other people is ultimately temporary; only God's approval can last for eternity.It is important to build a life on a solid foundation, meaning the gospel recorded in the Word of God (1 Corinthians 3:10–15; 4:6). Jesus told a story about two builders, one wise and the other foolish (Matthew 7:24–27). The wise man built his house on a solid, rocky foundation. This was a stable, reliable anchor for everything else the man constructed. The fool built on sand: something weak and vulnerable. The house with good foundations survived storms, while the one with bad foundations was lost. Perhaps the foolish man's house looked prettier than the other, and received glowing comments, but it did not survive. Similarly, from all outward appearance a wicked rich man's life may look successful and receive compliments, but it will not stand when death sweeps over it.
When death, the final storm, arrives, everything that rests on a flimsy foundation will come crashing down. However, life built on God's Word will survive death, and usher the wise person into a blissful eternity with God.
Psalm 49:13–20 further explains what happens to wicked people who trust in money rather than in God. Sheol—death and the grave—is their destiny. Righteous people should not be jealous of them or fear them. The rich leave everything behind when they die, no different than a poor person. For a second time, the writer compares physical death to that of animals.
The "riddle" in question is the fact that some rich persons are also wicked and ungodly. Rich and poor, alike, should remember that money is temporary. It is not a substitute for God's approval. All people face death and God's judgment. There is no reason to envy a person who has earthly wealth but lacks eternal hope.