If you want to borrow money to be used as BItcoin investment capital, that's fine, but borrowing it using a credit card in my opinion is less precise and more risky. Indeed crypto trading is risky but that is because of unstable market conditions that cannot be avoided. While in the capital stock we can design it ourselves, if it is too risky we can avoid it and use other methods. Moreover, capital is something that is basic when you are going to invest, so if the capital alone is problematic I'm not sure the trade will go well later.