@mysteryman,
A person can use a credit card and never pay interest.
Only charge what you can pay off when the bill comes due.
This allows you to keep earning interest on your money until you must pay the bill. And, depending on the credit card, can earn you points and money back. And is a great way to build a good credit rating.
Credit cards are only as bad as the people who use them.
Don't charge what you can't afford.