The short version [0] and the long one [1]

[0] https://kenkarlo.com/articles/the-scamming-of-tether-on-bitf...

[1] https://www.kalzumeus.com/2019/10/28/tether-and-bitfinex/

USDT is another "cryptocurrency". I put that in quotes as they can print it at their leisure. They claim to be backed by USD but have never been audited. The market cap grows by billions a month.

BTC and USDT is a common trading pair on crypto exchanges.

As a result, those behind USDT can print it and buy BTC to manipulate the price.

Don't get me started on exchanges allowing you to trade with yourself. This field is tainted with shady practices.

How hard?

People are buying and selling tons of BTC with USDT and if it ends up being a fractional reserve and has been printing billions with nothing backing it up, how much of the BTC price might've come out of thin air?