The concept of Nash equilibrium doesn't apply to a poker player facing two or more human opponents at the table, since they are likely not playing optimally or

The concept of Nash equilibrium doesn't apply to a poker player facing two or more human opponents at the table, since they are likely not playing optimally or even non-cooperatively, e.g. if there is a communication channel such as facial expressions (however poker-faced) that a robot player is not privy to. In the case of a poker tournament where there are at least a few non-optimal players, it's advantageous to exploit and take chips from them before other players do. A player who plays as though all of his opponents are playing optimally probably plays too conservatively in that early stage and no doubt faces a significant (non-optimal) disadvantage. Your comments still apply to heads-up (two person) poker, though.