It would not be that difficult to guarantee Tether price if tether actually did what they originally claimed. Take usd in, store that in diversified bank accounts/liquid treasuries, and if there ever is downward pressure on the Tether price, use your high quality liquid reserves to buy Tether back (while making profit!). And of course, if you are open and audited on your operations, there is very little reason for a downward pressure for the price.

Now, of course, if you decided to _not_ be open and _not_ hold your reserves in safe assets but instead decided to invest the reserves to speculative gambling tokens or shady commercial papers, then it really is difficult to keep the guarantee if the gambling token loses value.