I do agree that loaning money to invest solely on crypto is not a great idea. Loans need to be paid on the contract signed. When you invest in crypto, you won't have that assurance that you'll accumulate enough to repay the loan itself.
Actually I don't blame your opinion, but what I think at this time is that borrowing to invest is not a very bad thing if managed properly. Before we borrow, we also have to measure our ability to pay it like what, and can we if the loan is not successful in the sense of being unproductive? For example, MSTR is a company that issues bonds to finance their investments in crypto. I also dare to say that their investment is quite good in terms of the profit earned, so it is not a very bad choice if we have judged ourselves worthy or not in managing it.