The brother in humble circumstances ought to take pride in his high position.To properly understand this verse, you need to take a peek at the next verse. Once you do, the meaning of the "humble circumstances" becomes clear. We have shifted slightly in this passage to the topic of money. But it is not a complete shift, because as many of us would attest to, money is a trial in and of itself.
This verse reminds me of how God seems to enjoy turning everything upside down... or maybe it is upside up. Maybe we have things so twisted and distorted that it only seems that way to us. Regardless, in this case, the low is really high, and the high is low.
This verse is speaking of a Christian brother, who James is telling that he has the ability to boast in something. Even though most would say that this man has nothing to boast about, the "humble circumstances" can be defined as, "barely off the ground". Yet James says that even though he is barely off the ground, he is in the heights! As one who is a child of God, there is plenty to boast of.
Consider this today. God gives and God takes away. Don't let possessions fool you.