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But the question is what if you do not own enough money for investing? can you take a loan and invest?
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I will certainly take out a loan to buy more Bitcoins when the market experiences inflation...
Of course this is a very big risk, but that doesn't mean it's a bad idea either (taking loan to buy investment assets). I once worked in a restaurant and the restaurant owner often took loans to the bank, he said "that opportunity only happens once, why not try it even though it's risky".
The issue is that while the loaned money could be the same, the use that you will give to it is different, if you invest that money in a business that is producing profits already then you can increase your profits and pay the loan, when it comes to bitcoin you have no control at all of what the market does, and this means that the interest could become so high that even if the price eventually went up you will earn nothing, so I do not think this is a good idea.