Which they cannot do because 1) they don't have any banking and 2) they cannot allow redemptions which would risk a run on their reserves (to the degree those exist at all).
Nobody in the history of crypto has ever attempted it or no one has ever demonstrated it? It seems improbable no one has ever attempted it. And there's no reason to demonstrate if it is successful. So I'd argue the lack of failed demonstrations is evidence that it works.
