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.
This is not a good idea in my opinion, we are not talking about shark tank type of investement on campany that need growth and guidance, an investor added value is only his paycheck, so that means that you have nothing to win from it, you get his money to buy stuff, you mine he gets a huge proportion out of it, you lose he gets all the gear to pay himself and you have nothing left.
The best is always to start small and expend, unless there are credit with 0 % or low interest rate and you are sure to pay them back