I would say no to this proposal. I know bitcoin is a good asset and can be a good investment. But the main reason is bitcoin is so unstable and price is volatile. You can't say where will be the price of bitcoin go tomorrow. So, I can't buy bitcoin with a loan. I will take the risk till it's my own money.
You're right. It is always good to risk your own money than borrowed money. I experienced personally in my life. I had little amount of bitcoin in my wallet, but I took loan to fulfill some home needs considering there'll be growth with bitcoin. My prediction went wrong and now I'm in debt paying interest. If I've sold at the right time I could've avoided debt.