I think what happened was that all the old veteran players created those gangs in that list. In a way, they represent the top tier of PK'ers. Then, all the newer players that make it to the top just join one of those top gangs. I think M2S is the newest gang in the top list right? It's incredibly difficult to break into that top list because that's where all the good players are taking up pretty much all bases. According to your list, only Mafia is left free.