Also we've been there (mtgox's willy etc). I don't think bitcoin will be much less volatile any time soon. https://www.youtube.com/watch?v=XbZ8zDpX2Mg
People trying to get out of USDT into BTC because the USDT:USD parity assumption collapses will boost BTC:USDT prices, but probably not enough to avoid dropping BTC:USD, because it would be less than the USDT:USD drop, is the idea.
Thise specific USDT pairings would crash. If they wanted USD (as they presumably do), they’d then crash the other stable coin or backed pairings.
In the same way that there's no obvious ceiling to its value, if a lot of people try to get out of it at once, there's no obvious floor either.
Basically the market cap of BTC is not relevant here, but rather the daily volume.
Well, it will be an interesting week for sure.