Well of course there will be individual specimens of the same species, and even breeding, that have different individual characters.
But hundreds of years of breeding for aggression and actual combat have made betta a purpose built fish. Relatively recently much breeding has gone more towards show characteristics, but I'm not including betta with that heritage in this.
It sounds to me like youre comparing a pit bull and a wolf. My pit bull (or betta) is more suited for one on one combat with an adversary not unlike itself because it has been bred specifically for characteristics advantageous to that end. But your wolf (or predatory fish) is certainly better suited for attacking prey and surviving against a variety of adversaries because it has evolved naturally with characteristics lending themselves to be successful at that.
In short, throwing my baddest betta in your pond with your conglomerate of predatory fish would not end well for my betta. Nor would it prove anything at all. The betta is a mini monster, in my opinion. They attack and are generally extremely aggressive to anything in their area. If at the end of the day that's all they are, then that's ok with me.
