The difference is that the home is not liquid. It's not money. This is why you don't spend it and instead offer it as collateral. If I already have money in pocket, there is no reason to use it to get a loan of money.

But you say you don't want to spend it because it appreciate in value. And THIS is why this financial product actually exist for. It's a way to short fiat like I said before. The only reason to use good money to borrow bad money is to leverage the NGU of the good money.