Covetousness is a disease rooted in vanity. The simple meaning of the comparison is that it is better for a man to be content with what he already has, with what he can see with his eyes because it is already in front of him and in his possession, than to be hankering after what he does not have and can only reach out for with his desire.
Are you on the treadmill of desire, continually chasing after the wind? Listen to what Scripture has to say about this malady. Realise that you are trying to fill the emptiness within your soul with something that can never satisfy it. The soul belongs to eternity, but this world is passing away. Understand the root cause of your dissatisfaction: your refusal to come to God for life. Covetousness is called idolatry in the Bible just because we are trying to substitute created things in the place of God, but the soul will not be cheated in this way. Only the Christian can find true contentment with what he has because he looks to God to supply his needs and is thankful for what he has already received. It is not up to him to provide earthly security for himself but he happily yields that responsibility to the Lord who can do it far better than he can. God is his never-ending supply, and the love of God for his soul ensures that the Lord will never fail to provide what he needs. His love is fixed on the Giver himself rather than on what he gives, for the Giver is greater than all of his gifts put together. The unbeliever needs realism to come into him.