don't really agree with you because there is still the possibility of a bank borrower making a profit if he/she invests his/her loan in the long term...
if have low interest rates and can pay in installments over several years then why not borrow money from a bank for crypto investments because not everyone has cash or large assets for them to buy into Bitcoin for example. even though it is risky and too wild, but if you are right in choosing the coins you want to invest, then you will definitely make big profits.
If you invest borrowed money, you invest money you don't afford to lose. And then you've already lost.
Crypto price is fluctuating a lot. And since your strategy contains only the parts where you profit, in the moments the price goes down you'll panic and probably sell at a loss.
So again: if you break the "don't invest money you don't afford to lose" rule, you'll lose. And if you invest borrowed money, you do break that rule.
But no worries, you don't have to go by what I'm saying, you're free to make your own mistakes.