Not just Tether but all ‘stable coins’ are actually a risky investment.
The 1:1 peg to fiat/paper currency are just a promise and not a guarantee.
The total crypto-currency market cap - amount of coins/tokens multiplied by market price is 2.6+ trillion ‘stable coin’ dollars.
Yet the amount of fiat/paper currency collected is less than $100 billion.
The dominant direction of flow of value is from fiat/paper currency to crypto-currency - from people entering the market or to increase their holdings.
If a fraction of the flow reverses back - from crypto to fiat the coin/token prices will crash and the stable coin ‘peg’ will be broken.
More details in this article -
The danger in the stable coins (thought experiments and the real price of Bitcoin)
