What went wrong? Other than a cryptocurrency "stable coin" that was doomed to fail, backed by a Ponzi scheme (Anchor).

Here is a though exercise for the author and readers.

Fidelity Investments has a "stable coin" that is backed one-to-one by actual tradable low volatility assets which are fully disclosed and audited. No Tether style "secret sauce" that can't be disclosed or audited.

Compare and contrast the Fidelity Investments stable coin with Terra/Luna.

Then ask again: ah, gee, what went wrong with Terra/Luna?