Think about the time when banks vigorously promoted bank cards, that is, ordinary debit cards. They were free at the time, but now they charge a fee.
The same goes for credit cards. The current vigorous promotion is mainly to cultivate the market and make you feel that credit cards are useful and cannot be separated from them. We will gradually charge fees when the market matures.
Of course, the main purpose of the bank is to stimulate your consumption. Because credit cards can indeed stimulate your desire to consume psychologically, the bank charges a handling fee for every purchase.
Going deeper, there must be economic and financial reasons, but I don’t understand~~