T&C usually restrict using gift cards to purchase other gift cards (inter alia for the reason you mentioned) [1]. [1] https://www.amazon.com/gp/help/customer/d

T&C usually restrict using gift cards to purchase other gift cards (inter alia for the reason you mentioned) [1]. [1] https://www.amazon.com/gp/help/customer/display.html?nodeId=3122091 https://www.amazon.com/gp/help/customer/display.html?nodeId=... (see under 2. Limitations.)