[digsy]

Are they?

Visa/Mastercard charge merchants 1-2% interchange fees for each transaction.

I'd guess that people putting $20k a month on their Visa (I know a few that do) are paying for themselves with the interchange fees.

[ryanwatkins]

The vast majority of that fee that merchants pay goes to the bank, not Visa or Mastercard. And a vast majority of what the bank gets in that fee goes back out to the card owner in the form of rewards. You see merchant fees of 1-2% because that is pretty close to typical rewards paid out on credit cards.