For comparison there are 7.5 bn USDC circulating and these are emitted by Centre/Coinbase and these are known to be real (Coinbase being an HN unicorn to soon do its IPO).
Tesla also just bought 1.5 bn of Bitcoin.
Then are regular people buying directly with non USD currencies like EUR / JPY etc. (for which I take it there are no USDC emitted).
So it's a known fact that money is flowing, by the billions, into Bitcoin.
The question is: is iFinex/Bitfinex/tether printing USDT out of thin air by so many billions that they are actually manipulating the entire market?
Tether backing is not just dollar. They recursively use bitcoin as part of their reserve. Bitcoin price rises, and they print more usdt to buy more btc.
It's hard to say how much btc would drop or pump.
Tether bootstrapped crypto demand, even if it was done so fraudulently
I know for a fact that many traders are using makerdao to leverage their crypto holdings to buy even more crypto, so there's definitely a circular money pump that happens (for example: WBTC-A vaults have an outstanding 240M$ debt, presumably significant chunk is used to buy back more BTC).
Fun fact: USDC is not backed by real USD. Circle is using these dollars for its trading purposes and that's actually in the ToS.
Pretty much no stable coin is: https://omarabid.com/usd-stable-coins
That is really weird. From the link you gave: "you agree Circle is free to use the funds provided for its own purposes".
As you wrote: it may be the case that no stable coin actually is stable.
gemini dollars, maybe?