[LeifCarrotson]

A few points:

1. The only party benefitting from the cashback scheme is, of course, the middleman. While prices will go up in the long term, consumers who use cash-back cards do benefit in the short term over those who don't. If you make a transaction in cash or with a debit card which you could have made with a cash-back card, you are leaving 3% on the table. I am extremely skeptical that an individual boycott will be effective. Maybe take your 3% and pool it to lobby for better banking regulations?

2. they entirely eliminate the necessity for such middlemen taking a cut - AFAIK, all cryptocurrency includes some sort of transaction fee.