Above all: why do exchanges not implement a trading halt when the price drops by more than 50% in a few hours...

After the fraud - USTD $OM , Modalai committed another fraud where the price dropped from $35 to $0.800 on the same day, and now it has dropped to $0.070. Why do exchanges list such currencies? In the world of cryptocurrencies, no matter how much you earn, one scam can wipe out all your money. There is no one to ask or hold accountable — even the exchanges seem to be part of the scam.