Yobit is an long standing exchange, not one I would use
Yobit Pro was a scam app pretending to be related to that exchange
Crypto returns can be quite fast. If you have $4 million and its not really absurd to take that an order of magnitude higher, and be used to the volatility of it going lower.
There are plenty of “random crypto apps” that work fine for any amount of money
Don't let your own paranoia get in the way
“Not your keys, not your coin” remains true for “Yobit Pro”, FTX and established players like Coinbase
Plenty of random crypto apps are self custody apps that work fine
The people running Yobit Pro are probably using similar levels of OPSEC, and just have a lot more crypto now. This PvP aspect of crypto keeps it going.