Five Below (FIVE 1.22%) is something of a specialty retailer whose name no longer makes a whole lot of sense. In the beginning everything it sold cost less than $5, but that has since changed. That speaks to the big issue investors need to consider when looking at the stock and wondering whether it could help them retire as a millionaire. The answer is, it could, but -- and the "but" here is really important.There are things to like about Five BelowShares of Five Below have plunged over the past year or so, ...