It recently occurred to me, with the whole LUNA fiasco, that any "stablecoin" that is 1-1 backed by fiat can come under attack from leveraged traders, and get de-pegged. So it really doesn't matter what backing tether has, although more is obviously better. When the music stops it's anyone's guess what will happen.
Any stablecoin that is NOT backed 1-1 by fiat, correct? I.e., algorithmic stables. If you're 100% collateralized by USD in your bank account, how can it get de-pegged?
If there was no leverage, then yes, a 1:1 backed stablecoin would hold it's value.
EDIT: I mean the story here is far from clear, you also need to consider arbitrage bots that act between exchanges, etc. etc.