Instead of using credit card, approach people with money to invest with you. People with money would love to get into crypto. If youve built mining rigs, you can put together a simple business case.
Its always dumb to use your own money, its even dumber to use money you dont have (credit). Use someone elses money and give them a nice ROI while you get a decent returns as well. Spread the risk and increase your profit.
There's no difference from your perspective using a credit card vs borrowing money from an investor. The investor is the credit card in your scenario, and depending on the deal you made, they could have a perpetual stake in your mining profits.