Although I won't go so far as to say it is a big ponzi scheme since terra is actually trying to do something to fix this plus the fact that btc dropped like hell making luna and ust follow, I cannot assure otherwise as well. Because even with the fact that I am a huge fan of luna(but did not have ust, lol), I definitely cannot trust their ust anymore stabke coins should be somewhat immune to btc crashes but ust dropped like hell along with btc. I might buy a bit though just for speculative profit potential but nothing more than 2% of my capital.