Yes, you're actually correct, I am purchasing nothing. I charge my card, using amazon payments. I withdraw to $$ my bank, I pay my credit card in full. I do this 3x a month. So I pay myself $3000, and pay the cards $3000. Net = zero.
The only gain is I'm awarded points for using the card - 2% which is $60 in giftcards monthly. It's a lil work, but takes 5 minutes the first day of each month. $60 a month, $720 a year, x years, it adds up.
Heck that makes my internet free
Just setup an Amazon payments account for each person in your house, you can expand as much as you can.
Amazon used to have a higher limit of spending without being charged, but they capped it at 1k a month per account, to limit this.