The tight trading with USD may actually be an indication of trust in Tether. It indicates that at least one entity has enough confidence that it is worth exactly $1 that they are willing to buy or sell whenever it fluctuates from that price.
If that trust is ever lost, or there are questions about solvency, I'd expect the price of Tether to drop very quickly.
It only takes one person really sure about Tether to have a bot which simply always trades to keep the price at 1 USD.
That person might be an insider (they know tether is legit, so any deviation from $1 is a moneymaking opportunity), or it could be an outsider who believes the hype.
The very first paragraph opens comparing this to "defying gravity". Your assumption were true it would make it very easy for others to win at all times. Think about it for a second: there is someone buying and selling, consistently at known price points.
> Think about it for a second: there is someone buying and selling, consistently at known price points.
This happens all the time in the stock market. Look at the SPY stock which tracks the S&P 500 index. At everypoint in time, anyone can compute exactly what value this stock should have. Any deviation from this consistent and known price point is immediately traded away by arbitrators.
The difference is index funds actually hold the underlying basket of assets for the index they track.
Does Tether actually hold one real United States Dollar for every USDT they issue? If so, they sure haven't convincingly demonstrated it by continually lying about being regularly audited (they have never published a real audit) and refusing to allow anyone to redeem their USDT with Tether to get back a USD.
If that trust is ever lost, or there are questions about solvency, I'd expect the price of Tether to drop very quickly.