and the rich (boast) in his humiliation, because like a flower of the grass he will pass away. (ESV)
What do you boast about? Most people boast about having possessions. We like to show off the things that we have that someone else does not have. Money has a way of enticing us to boasting. Perhaps you have a collection of antiques, fancy cars, or even bank accounts! It is tempting to boast about having all of those things.
James gives instruction to the believer in Jesus Christ who are rich. They are encouraged to boast! But their boasting is not what you would expect. They are to boast in their humiliation. Now that does not sound like something to boast about. Who in the world would have all kinds of wealth and boast about humiliation. I know someone.
 who, though he (Jesus) was in the form of God, did not count equality with God a thing to be grasped,  but emptied himself, by taking the form of a servant, being born in the likeness of men. (ESV)
The ultimate example of humiliation is that of Jesus Christ laying aside all the wealth of heaven to be born as a man. He took the form of a servant, not a king. He was born in a stable, not a castle. He had all wealth, but wealth did not have him. The Apostle Paul told the Philippians that the same mindset that the Savior had should be our mindset.
Are you rich? Boast in humiliation. Do not celebrate earthly wealth. You have nothing that the Lord did not allow you to have. Be generous to the Lord and to the church. Be like your Savior.