Cryptocurrency fraud DEX

Centralized exchanges for example coin base or others are legal entities and have a legal entity similar to an individual and are owned by shareholders or other individuals and are commonly regulated to some extent however assume this is somehow a realistic idea or question is it possible to defraud a decentralized cryptocurrency exchange given these factors 1. There is no owners 2. No other account holders are hurt in any meaningful way this only affects your account etc 3. The platform involved fiat and the scheme involves fiat unlikely I know but just for the question and lastly it’s decentralized with these factors in mind would it be possible to prove fraud in a criminal and civil context in the United States or elsewhere?