I agree with everything you said, but you do have to be careful with this. There are many studies that suggest we tend to spend more using credit cards than we otherwise would. Up to 18%. Spending 18% to save 3% doesn't work. Just a note of caution. If you are disciplined he is definitely right. But I've never had the answer to how did you get rich be "it was the airline miles"
Unfortunately, those same studies (you're referencing a Dun & Bradstreet study with that 18%) show that debit cards with a VISA/MasterCard logo on them increase spending just as much. It's all about the lack of transparency, i.e. it hurts less to pay with plastic.
That is unfortunate, but I never said you should use debit instead. Though if I remember correctly the study suggest that debit spends more than cash, but less than credit.
FWIW I use a debit card most of the time because it is much more convenient than cash with the knowledge that I am spending more than I otherwise would.
