A loan to buy a cryptocurrency is not the best solution. I would even say that this is a crime against risk management. However, this can be done by following certain safety rules.
1. Borrow only the amount that you can pay off without any problems, even if you lose all your bitcoins.
2. As soon as after the purchase the value doubles, sell half of your bitcoins and repay the loan.
At some instances of life where some of our colleagues couldn't afford to buy or have their own kind of bitcoin right away then this could be their best way to have it, taking a loan to buy bitcoin. But in my own opinion it isn't the best solution since i am afraid to the mere fact that this was a total taking of risk. I am afraid to the fact that it can be lost with just a glimpse. I didn't mean that taking a loan for the sake of bitcoin wasn't worth it, but i guess it should take seriously, should need a wise decision.