[HesseJam]

You are treating the problem with the wrong tool: the EV concept. You should apply EV as a decision tool only in repetitive situations.

This is a once in a lifetime situation for most players. It will never come up again. If you play it out the result will be either 2 Mio or 18 Mio which is a big difference for both stacks.

You need to analize the risk/utility function of each bargaining side (your own and your opponents).

If I am the small stack I get 2 Mio for sure. This will provide some financial security for me and my family. I am happy. But I have a small shot at getting filthy rich from a save point. I gonna take that shot! I have nothing to lose and a lot to gain.

The big stack is very close to becoming filthy rich. It is not going to take a lot to get there. However, there is that risk of falling back to just being financially secured. He does not have a lot to gain at this moment but a lot to loose.

El Diablo above offered 1 Mio. He simply traded the difference between a) his personal utility values of 2 Mio$ and 18 Mio $ respectively multiplied by the rate of risk he will forego this difference for b) his personal difference between the utility values of 17 and 18 Mio$. I think he is seriously lowballing here and should be happy to give up more. Whats the difference of winning 18 or 16 Mio$? Well it is 2 Mio $, right. But 2 Mio$ mean a lot less to somebody who has 16 Mio $ than to somebody who has 2 Mio$ which would be the outcome if he lost.

But wait, maybe he is just negotiating well! He tries to assess my risk utility function. What may it be worth to me to get additional 1 Mio$. It may mean a lot! My financial security would be up by 50%. OTH since I am already more or less financially secured it may not be enough that I give up the shot at the additional 16 Mio$ and become filthy rich. I personally could live with the decision to turn down the additional 1Mio $, take the shot and lose. I'd be also happy with my 2 Mio.

Could El Diablo make his peace with his 2 Mio in the small likelihood that he lost the battle under the assumption that the battle could have been over if he had offered 2Mio and settled for 16 Mio?