You know better the system of credit and debit card
Actually it’s not an extra or reward money which they give us with the name of bonus and offer etc. When we pay by credit to a seller they charge service charges from seller and that’s why seller fixes his price for any goods keeping all these charge so as much as a customer uses the credit or debit card they both ( seller and bank) make their profit therefore there is nothing wrong to get this offer or bonus money. At the end it’s yours and ours.