First of all, it is a breach of contract not to repay after the credit card is overdrawn. The bank may require the cardholder to repay the principal, overdue interest, late payment fee and over-limit fee. If the bank sues the court and wins, the cardholder will also bear the litigation costs.
Secondly, if the cardholder maliciously overdraws a certain amount for the purpose of illegal possession and fails to pay it back within the time limit, which constitutes the crime of credit card fraud, he should also bear criminal responsibility.
Finally, overdue repayment will leave a bad credit record for cardholders, which will affect the smooth progress of cardholders' future loans and other behaviors.