Most attempts at "algorithmic" stable coins have failed. See TerraDollar, Luna and Titan.
And you just know that the "collaterized" ones are? In most cases, their books aren't open. And they wouldn't lie about this would they?
In some strange way, the crypto brain has been programmed to ignore the obvious with a hand wave and just accept all the chicanery that is crypto.
Maker initially worked same way, but eventually they started accepting off-chain collateral.
Most attempts at "algorithmic" stable coins have failed. See TerraDollar, Luna and Titan.