The idea sounds of taking a loan and investing in Bitcoin sound kind of attractive, when you think about it this way: You take a loan and invest in Bitcoin when the price is down and sell off to repay when the price goes up. But the honest truth is that when we take a closer look at the idea there are some risks attached to it. One of such risk is Emotional Stress. Now owing someone( debt) is already stressful and burdensome on it's own, now combining it with Bitcoin's volatility can make an investor feel pressured and lose sight of the bigger picture which is that Bitcoin reward comes in the long term and then that investor may be forced into panicking, and even selling off at the wrong time.
I understand your point, carry load to invest really sound attractive because many people assume it that they can buy bitcoin when price is low and wait for price to raise so that they can sell, but the reality is that bitcoin at times doesn’t move as anyone expectations, and one of the biggest mistake person can made is to think that bitcoin will go up at a time when the loan repayments is due.
One of the reasons why I wouldn’t advise anybody to carry load to invest in bitcoin is that, debt creates unnecessary pressure, and that pressure can lead you to make a poor decision, instead of you thinking long term, you become obsessed with short time, and if things no move as your expectation you become panic and sell your bitcoin to repay the loan which is bad decision.