A subset of credit card holders use them extensively and strategically to gain rewards.<br />They tend to be very savvy, know all the rules and angles, and can eat away at a bank's profits.<br />Now, Business Insider reports that some card issuers, like JPMorgan Chase, are onto them.<br />Reports suggest Chase may be taking a harder line with credit-card gamers who open too many accounts.<br />As such, they're closing the accounts of so-called 'super users.' <br />
