Taking a loan means that you have to repay the loan in any way, and investing in Bitcoin with a loan means that if you cannot achieve success from this investment, then you will not be able to repay your loan. Now the question is, Since you are investing in Bitcoin with debt, Is the success of your investment guaranteed? Bitcoin is a currency thats moves very volatilely, so there is no guarantee that you will succeed here, now that there is no guarantee of success here, then how can you invest beyond your means here? Even with a loan, which you have to return with more interest after a certain time? Making such a decision is definitely very foolish, market fluctuations can cause losses in an instant, and then it will be difficult to repay the loan, so you have to invest with what you can afford to lose, decide to invest from discretionary income.
Before going for a loan, you need to understand whether you can afford to repay the loan. If you take a risk without understanding anything, then it will never be the right approach. So you first need to understand whether you can repay the loan from the thing you are taking a loan on. There are many who take risks to invest by taking a loan, but they think separately that if the investment loses, then they can borrow money from somewhere else and repay the loan. If you have an income to repay the loan, then it will not be bad to invest with a loan. But
There are many who do not have the means to repay the loan, they invest with a loan. This will never be the right decision. If those who do not have the means to repay the loan, if their investment loses once, then they will be in a very bad situation and it will basically be like gambling with their lives.
You are correct, most big investors do go to the banks to collect loan, first the banks checks at their properties and asset to use as collateral, before granting their loan request, Banks just don't give them loan without proper check. So the idea of collecting loan to invest isn't a bad one, but the process of repayment is the actual thing, so once your collecting a loan, make sure you have the means to payback, even when the actual thing you collected the loan for isn't giving you result yet.