Since you are retired, you really don’t need a credit score for much stuff anymore

Getting 5% cash back is fine, except when someone spends 40% more on items they weren’t going to buy. How many people go to dinner and overspend? How many go shopping without a budget and overspend? If you spent $100 to get $5 back, you could have spent $90 and save the $10. Responsible people will pay off a credit card each month, but you have to ask yourself, how much of the actual spending was over budget or unnecessary? If your water bill went up to $500, you would probably cut back to a normal amount.