1. You have to pay a high monthly package fee: even if you don't use the card, you have to pay the monthly package fee, which may increase unnecessary expenses.

2. It is not conducive to the effective use of funds: the main card that has been idle for a long time occupies a part of funds, which may make it impossible to use this part of funds for other more valuable investments or consumption.

3. Increase management difficulty: For users with multiple mobile phone cards, managing the fees, packages and traffic of multiple cards will increase management difficulty and make mistakes easily.

4. Increase the security risk: The main card that has been idle for a long time may be used by criminals for illegal activities, such as fraud and spam messages, which increases the security risk.

5. Impact on credit record: If the master card defaults or defaults, it may have a negative impact on the user's credit record and affect future loans and credit card applications.