What is the advantage of paying your credit card balance in full each month?
You will incur only a small "paid in full" fee on your next credit card statement.
You pay only a small amount of interest.
You have less of your credit limit available, therefore, less temptation to spend.
You avoid paying any interest and fees.
It's the third one. You avoid paying fees and interest. Smart people keep their credit cards at a zero balance for just that reason. Moral: don't buy what you cannot afford to pay off immediately.