If one has ever experienced the bad side of taking a loan from the loan shark then they would have understand the more reason it is not advisable to buy bitcoin on loan, investing on bitcoin maybe on a long duration while the loan taken may only last for few months in which when the time to make repayment completes and you're not capable of doing so because no interest has been marginalized yet, this make it part of the reason why it's not good for taking loan to invest.