The thematic verse for these Scriptures has to be found in Proverbs 16:18-19 where we read: "Pride goes before destruction, and a haughty spirit before a fall." While the Psalms that we read are much more comples than this simple verse, there is a truth to this simplicity which is carried out in what we read for today. While David extols the steadfast love of the Lord in Psalm 36 he still warns the evildoers that they will receive their recompense.
David says something curious that should strike us as not really reflecting the reality in which we live. Look at Psalm 37:25 and you read: "I have been young, and now am old, yet I have not seen the righteous forsaken or their children begging bread." Well, that would assume that those who beg for bread are not righteous, I'm not a huge fan of this type of thinking.