Taking loan for investment is not recommended and its not only limited for crypto and if someone can't calculate the possibility of losing money because of their investment they can get bankrupt. It's better to start investment with small money and to understand how investment works instead of taking loan just to speculate because not every investment can become successful.
People who do loan into investment or maybe trading in crypto, they usually already gain profit in their first trade. Then they think to loan because they really confidence if they will keep getting profit and then can pay it. But mostly at the end they are lose and then really suffer to earn money to pay what they borrow, that is why a lot of people never suggest it to other.
It's many newbie mistake to be overconfident and make bad decision because their first success making them thinking they will always success