Not just that what if the stock market crashes and suddenly you have no cash access? They get to keep your cryptos. Banks etc know the market will crash and this way if people are not careful with the loans the banks will remain with cryptos and you with nothing, assuming you don't invest it back into cryptos. It is a great idea people just need to be careful. A loan is a serious endeavor no matter if it takes place in a bank or in cryptos.