So at least one has gone down, but for sure there will be another criminal gangs and so the crime will not stop and so are the police trying to hunt them down. And even if they try to hide it within crypto networks they are going to track them down.
I have to say, the fraud amount from investment and BEC attacks is really significant, but only four arrests? For an operation this size? The rest are still out there because every time the mules are the only ones who get caught, the architects are always free. At least most of the time.
In crypto, it is quite hard to trace the money even if it is on-chain, unlike banks. Because these hackers are mixing them, exchanging them, even via centralized exchanges, and using fake accounts by buying them from dark markets to launder the money.