So far we have come to know about many scams and many scams have been discussed in this forum. The biggest fraud I have seen and known is the SBF fraud. The fraud committed by FTX is considered to be one of the biggest frauds ever. Investors have lost huge amounts of money due to this scam and many investors have lost confidence in crypto platforms and exchanges.
Yes. FTX is one of the biggest but not the biggest of all I believe when considering mt.gox and in terms of BTC. With that said, many people are used to it. They can lose their confidence but that is only for a while and later on they will come back again.
Mixer campaigns have cheated but those cheats are nothing compared to the FTX cheat because the FTX cheat is one of the biggest cheats I have ever seen. SBF was heavily penalized for this massive fraud even though investors did not get their money back due to his conviction.
Are you referring in the mixer signature campaign in the forum? Maybe some are cheaters, in a way that they don't pay the manager and their participants. If you are only referring on the mixer itself/alone, again maybe some can cheat because they don't return their customer's coin. For the legit ones, I think you can't call them a cheater because their primary purpose is only to enhance the user's privacy. And I think not all who does that are cheaters.
Maybe millions, billions, and so on... dollars can be involved sometimes. So, it is actually possible that they can be bigger than the amount involved in the FTX scandal but the case of FTX is different. They are more harsh since a lot of people have been affected.