If the person's financial situation is stable and the banker, after studying the file in depth, is OK, I don't see why you can't borrow money to buy BTC. In fact, this is what some large companies do.
I agree but a person with a stable financial situation shouldn't borrow to invest in an unstable asset because the risk involves means that they may now go into debt if the market crashes. But I know that there are people who like to take risk and are ready to deal with whatever comes.
You have a point there, but even those wealthy men in the society still take some bank loans so they can finance their investment, regardless if it’s high risky or not.