Is it permissible to use a secured credit card with websites belonging to companies that support activities like gambling, in order to purchase foreign currencies and benefit from the exchange rate difference?

It is permissible to purchase currencies using a covered card, as long as constructive possession is achieved. The banking entry of a sum of money into the customer's account is considered constructive possession. It should be noted that the beneficiary is not permitted to dispose of the currency during the tolerated period, except after the effect of the banking entry has materialized through the possibility of actual receipt.