When you are involved long enough with crypto, you'll see a lot of stupid ideas. DAI is one of them.
For those who don't have time to get into the weeds, DAI is a "digital native" stable coin. It wants to create a 1-1 peg to USD using an underlying volatile asset, Ethereum. If you want to use USD, it's probably most efficient to go get USD. :) But for some ideological reasons (decentralization), DAI wants to be USD but also digital native. So they "lock" the underlying asset, Ethereum, and issue DAI coins. The premise is with intelligent computer algorithms, we can maintain 1-1 peg between a digital asset (Ethereum) and a real-world asset (USD).
Digital assets are digital. Humans are the arbitrageurs. Humans are emotional. DAI is trying to create stability on top of Ethereum volatility. It's kinda like building a stable house on a shaky foundation. Your building will either collapse or you spend so much money patching the flaws of your shaky foundation. This is a laughable idea for those who live in reality. But I guess some computer programmers/investors live in alternative realities too long. They forget about reality.
Whatever your algorithms are, you need to arbitrage risks. So you will always need to lock up more USD-ETH to account for risks. To be safe, maybe, you need 1.5 USD-ETH for a DAI USD. However, with digital scarce and volatile assets like Ethereum, there's a chance that 1.5 USD-ETH will drop to 0.9 USD-ETH. At that point, you will be underwater. Yesterday, it did. If you need to lock up 1.5 USD for 1 USD, you may as well go get 1 USD. It's a dumb idea to use 1.5 USD to get 1 USD.
DAI has a lot of jargon and technology (more layers on top of the shaky foundation). These things make it look sophisticated and fool people. The basic problem is very simple. You only need elementary school arithmetic and logic to know its flaws and inefficiency.