The most revealing of the commandments. It indicates the presence or absence the most basic Christian virtues, faith and love. Covetousness grows out of a basic mistrust of God, especially in his care and provision for us. It therefor robs of one of life's highest blessing, contentment. Now godliness with contentment is great gain.
Covetousness reveals a real lack of love for our neighbors.
We must always remember how Jesus defined neighbor. Israel had just entered the Promised Land. They captured Jericho by the power of God. And you, by all means abstain from the accursed things, lest you become accursed when you take of the accursed things, and make the camp of Israel a curse, and trouble it. It meant that all that was in Jericho was devoted to God.