Because of impunity of fraudsters people lose their trust to cryptocurrency. Everybody can steal your money and do not have any punishment.
The steal of money has nothing to do with it. Scammers act more subtly, creating the conditions for voluntary investment. It's hard to blame someone when you give him your money.
In 2017 and 2018 many people believed too much in the perspectives of cryptocurrency and they gave a lot of money to scammers expecting to get a lot of profit.