Yeah.
It’s like free credit, minus the fees.
Said he made $300K. I’m not sure over what time span.
*He pulled the concept from personal-finance websites: Exploit the difference between unlimited 5% rewards and lower fees*
I’d have to read further, but it doesn’t sound like they taxed him for the rewards points per se, but on the cash generated between the 5% float between the cash back and the purchase of money orders.