The people who carry the highest credit card balances are often those who have money, not those who don’t, a new study found. But the combination of haves and have-nots in the same metro area drives up the percentage of creditors with five-figure card balances. The report, which was compiled by CompareCards, found that about one in six credit card holders in America’s 100 largest cities carries a balance of $10,000 or more, and that most of the cities with the largest percentages of people…