James is issuing a warning.
Keeping with the theme of the rest of the letter, he isn’t calling them out for being wealthy – he’s calling them out for for they are using their wealth and treating others. They used their money for fine clothes. They hoarded their wealth. They cheated their workers to line their own pockets. They were living a life of luxury while others were in need.
Earlier in the letter, James is telling them they should be treating one another well and doing good works In hoarding their wealth and cheating their workers, they were robbing themselves of the gift of being a blessing to someone else, as well as robbing that other person of receiving that blessing.
Do we do this?
Maybe we aren’t rich with money, but what about the gifts and talents God has blessed us with? Do we hoard them, keep them close and hidden? Or do we share them with the world, being a blessing to others and bringing glory to God?