> Except we used our cards to make $3,624 in spendable cash last year, all while paying zero in interest — because we paid the cards off in full each month. Yeah except the merchants probably marked up their prices 4% to cover card processing fees so really we are just paying more for goods than we otherwise would have with cash and the card company is giving us a tiny kickback. Let's not pretend credit card kickback…
Lastly have you tried paying with cash online? While Bitcoin is a neat idea we are far from yet mass acceptance of any digital currency yet.