You could, in theory, do exactly the same with cash. Get $10,000 credit card, go to ATM's over the next 10 days withdrawing the maximum amount ($1000) as a cash advance in USD, default on the loan and have $10,000 in USD cash. Of course you'd ruin your credit rating, probably be made bankrupt by the bank, the govt may even seize any assets in your name (house, car etc) as part of the bankruptcy proceedings.
How much would you have made if you purchased bitcoins 6 months ago using a credit card. You wouldnt need to default .
Only assuming BTC is increasing in value, which it has been, but then again so has the stock market over the last few months. But like any investment, whether it's shares or international currency or BTC or property, investments can go up as easily as they can go down.