A bank can decline a large debit-card purchase even when your account shows more than enough money to cover it. That does not necessarily mean the bank thinks you are broke. The transaction may have hit a daily purchase limit, triggered a security system, or run into a problem with your available balance.
Large purchases create an awkward little banking mystery. The money sits there, visible on the screen, while the card machine delivers a firm “declined.” Then comes the temptation to keep trying the card, move money around, or call the merchant before figuring out what actually stopped the transaction.