Do "unexploitable" strategy exist in No Limit Holdem? By this I mean frequency-based mixed strategy that has non-negative expected payoff against any other strategy (let's assume the game is completely symmetric, seats are randomly assigned to all players).
From my very basic understanding of game theory, I would say that for a 2-player game the answer is yes because any equilibrium strategy (which should exist, right?) will do the job. But what if there are >2 players?
I'm interested in a proof for the (non-)existence of such a strategy.
EDIT #1: As pointed out by vadim123, we should assume collusion is impossible.
EDIT #2: After thinking about it for a bit, I'm actually not sure whether collusion matters at all. Maybe someone can show a concrete example (with some kind of formal proof)?