Tu madre!

[fellfold]

I don't see how pot size affects the decision to three bet or not at the river. Assuming you are not folding to a 4 bet, you've already won what's in the middle or you haven't. When faced with a river bet you wont fold to, you options are to either call or raise.

If you decide to call, then your EV is a simple pot odds decision and you only have to be right a small percentage of the time to be right.

The EV of a 3-bet is more complicated. Assuming no one folds, the money in the pot is already going to the person with the best hand. The value of a raise is determined by how often you have the best hand. Your value is determined by how often (ignoring ties)

1. a hand you can beat calls you (you gain an extra bet)
2. a hand that beats you calls you (you lose an extra bet)
3. a hand that you beat 4-bets you (you gain two extra bets)
4. a hand that beats you 4-bets you (you lose two extra bets)

But these don't all happen with the same frequency. I would argue you need to be a marginal amount better than 50% to make a 3-bet profitable. Why? Because #4 is probably going to happen more often than #2 and #1 is going to happen WAY more often than #3.

So unless you have a good read that you are ahead, just call. In this case if you read the guy for a draw and the draw gets there and he raises you, call or fold. Given your read, 3-betting with the intent of extracting more money means you are just dreaming.

At the river, the gap concept is much different. You need a much better hand to raise than you need to call.