> They are the equivalent of remortgaging your home to get cash.

It's actually the opposite of remortgaging a home to get cash. Remortgaging a home to get cash is paying a premium to increase the amount of liquid assets available to you; this is the point of most loans. A DeFi loan is paying a premium and _decreasing_ the amount of liquid assets available to you. As you said, it's useful for juicing speculation, worthless for anything else.

> You get a stable and guaranteed >5% without all the risks of the stock market.

I think the long-term risks are actually greater than something like an index fund, since your collateral is all in crypto. The returns are also less than historical index fund returns.