ARMs are not fraudulent because the terms are clearly disclosed. If someone chooses to borrow money and agrees to unfavorable terms they have supposedly made an informed decision. ARMs are not Ponzi schemes, and there’s no rug pull or fake valuations. They are just bad financial decisions for a lot of people.
Even so, finding examples of scams or fraud or risky investments that aren’t crypto doesn’t validate crypto. People are capable of all kinds of scams and frauds. Crypto is just a near-perfect vehicle for scammers.
The ARMs in the 1980s in the United States were well-documented and the potential interest rate increase was both "rate-limited" and capped. They were not fraudulent.