These guys aren't going around announcing themselves and those that personally knows them aren't talking about them...most likely because of some collaboration to help each other.
Yet, once in awhile, Bloomberg will talk about some top institutional trader or top fund manager that decides to quit and trade their own private account...I'm guessing they are most likely trading a 7 figure account.
Just as importantly, they don't want to bring any scrupulous eyes on what they are doing just in case they want to return back to what they were doing before becoming private. Also, haven't you been reading lately the Bloomberg news stories about those 7 figure traders (extremely successful) getting caught spoofing and other illegal things ?
All you need to know that they are large and they are out there...doesn't matter exactly who they are and the specific 7 figure capital they have nor the 7 figure profits they're making...you just need to know they exist and its 7 figures and trading markets that the typical retail trader
doesn't trade.