Theoretically, the only way to stay on the plus side in terms of credit card rewards is to pay off your post-purchase balances in full to avoid interest charges, Brown says. Cash advances come with high fees. Buying cryptocurrency with a credit card may tempt you to spend more than you can afford with the hope of an investment paying big returns. Luckily, Chase viewed it as a purchase cash advances are a horrible idea with equally horrible interest rates , and he earned 1, Ultimate Rewards points. USAA was one of the first banks to invest in crypto exchange Coinbase and was named one of the most Bitcoin-friendly banks in America. The editorial content on CreditCards.