[AKQJ10]

Much to be said here, and Pov's points are good ones. However, I want to point out one important fallacy:

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Any time someone makes a +EV decision, it's -EV for you.

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This is very untrue. Exaggerated example: You're in the cutoff with AA, button has 7 [img]/images/graemlins/club.gif[/img] 6 [img]/images/graemlins/club.gif[/img]. 6 limp, you raise, button calls the raise (which as you say is correct with so many in the pot), blinds and limpers all call.

Flop (20 SB):

A [img]/images/graemlins/club.gif[/img] K [img]/images/graemlins/diamond.gif[/img] T [img]/images/graemlins/club.gif[/img]

Eight check, you bet (which must be correct -- you probably have the best hand and there's no way giving free cards to draws is correct here), button calls (or raises to get out single higher clubs in case two more clubs come, but the more I think about that play the less I like it)....

You and button have both played +EV here. The reason this is possible in a zero sum game is because the other eight have played so poorly, building a big pot. Button playing +EV isn't costing you money. Perhaps in the very strict sense that you would profit even more if he wrongly threw away the flush draw, it's costing you money. But that's not -EV for you; rather it's not as +EV as it would be if he made an egregious mistake. Him playing correctly is not cutting in to the huge profit you both have made from all those limpers in the pot.

Anyway, kind of a contrived example but my point is, with enough bad players in the game, one good player's +EV decisions aren't -EV for the other good player; they both can be playing in a way made profitable by all the other bad players. It's a zero sum game for the table as a whole (actually a negative-sum game with the rake) but not a zero-sum game between any two opponents unless they're heads-up.