[lofatdairy]

Here, $UST's justification was a 20% interest for holding. Thus, in theory, just by owning $UST, you make more than you would holding dollar bills (emphasis on "in theory"). Broadly speaking, the raison d'etre of stablecoins is liquidity. Interfacing between fiat and crypto is difficult for banking reasons and taxing reasons, but interfacing between crypto coins is easy. Thus, stablecoins are seen as a useful tool for both accounting, as well as being coins that are hedged against collapses (again, in theory).

[Fargoan]

You earn ~20% by converting UST to aUST. aUST earns interest from loans in Anchor and LFG pumping money into their reserves.

[pjc50]

Nobody asked where the other side of that trade was, did they? Borrowing UST at 20%?