Earlier quoted context omitted.
There is one scenario in which the 70 billion was at one time made-up money, but where it won't ever actually tank the crypto market: 1. Tether prints $1 billion with no backing. 2. Tether buys $1 billion of Bitcoin with the the fraudulent tokens. 3. Bitcoin triples in price. 4. Tether sells 1/3 of their position in exchange for hard currency, and holds that money in their reserves. 5. Tether now has 100% reserves ba…
It really can't happen this way. Between 3 and 4, you'd tank bitcoin's value significantly (assuming $1B is able to triple bitcoin's market value). Any sizeable liquidation of bitcoin at an inflated price is going to affect the price heavily and so now you no longer have 100% backing. (This of course depends on how elastic BTC/USDT price is)
$1b could also triple bitcoins price without the liquidity problems you're talking about because the initial purchase, done intelligently, can increase the price enough to kick-start another buying cycle (bitcoin goes up 100%, ends up on MSM news channels, people download coinbase and buy bitcoin, loop continues).