eremiah 17:5-10 is in many ways a sister to this passage. But, while David's focus was on "delighting in the law of God" Jeremiah's focus will be on trusting God. Of course, the 2 things go inseparably together (Romans 10:17), but they are not synonyms. God's Word can and should cultivate faith in us. And, as our faith increases, so too will the hunger which we have for God's truth.
But for now, the purpose of Psalm 1 is obviously to point out the distinct difference between the destiny of the righteous and the fate of the ungodly. All of God's children are righteous children... not because we do right all of the time, but because we have been regenerated. We have been adopted into God's righteous family. His righteousness has become our surname. And yes, naturally, we should strive to live in agreement with our tag (II Timothy 2:19). So anyway, this 6 verse Hebrew poem describes in part how a child of God is supposed to behave, as well as the common experience of those of us who submit to God.
It can't be accidental that we find this Psalm right on the heels of Job's biography in the canon of Scripture. Imagine if Job had written Psalm 1 on his deathbed... affirming the blessedness of the saints, despite his exceptional experience. It wouldn't have been out of place at all. So, after riding the choppy waves of the book of Job, it's refreshing to stand again on the solid ground of Psalm chapter one. Whether sooner or later: God's faithful children will become solidly fruitful trees; while those who remain as the devil's offspring will be taken out of the way like dead leaves in the wind.