Borrowing money for bitcoin investment is of course a good thing,
You'll have to pay the interest of that borrowed money. What if you've loaned money to buy bitcoin just after the bull run and the bear market came? This is the worry that many are thinking about because a lot of people did that before and they did it on the wrong time.
Not saying that someone can just do it on the right time because you'll never know the circumstances that you'll be facing on the right time and if you'll be able to borrow money. We all believe that the price of bitcoin will rise for the next couple of years but still, you'll be taking a debt and you're obliged to pay for it while we're not yet profiting from the purchased bitcoin and you'll have to pay it with the fees and interests.
I don’t think borrowing money is the right option when one decide to invest without money on hand. Particularly for a risky investment like bitcoin, you cannot expect it to pay your loan’s interest and fees every month because you don’t hold guarantees as to when will you become profitable from bitcoin investment. In the end, you will only end up having another debt to pay your first loan. Though bitcoin is a wise investment, but I cannot advise anyone to invest in it from a borrowed money or funds.