- USDT is a fictional currency invented by Bitfinex to make up for the fact they don't actually have access to banking because they're unbelivably shady.
- They got many other exchanges onboard since it effectively allows you to skirt AML and KYC regulations.
- Bitfinex is a shadowy cabal of truly dreadful market participants who mess around under the covers with Tether and use it to effectively control pricing. They print Tether and use it to buy BTC to drive the price up. They then sell BTC for Tether if they want to drive the price down.
- They promised for 5+ years that they'd get Tether's bank account audited but instead auditors up and quit.
- They had 30% of their assets seized in a money laundering sting but of course, the exchange rate remained 1:1 instead of 1:0.7
- The NYAG is suing them.
The price you see of BTC doesn't really reflect anything other than Bitfinex' manipulation. The rate of BTC inflation falling from 12.5BTC/block to 6.25/block affects miners and their ability to be solvent. Not much else.