Earlier quoted context omitted.
I don’t think your perspective is very useful, because you seem to be assuming that all commercial transactions are zero-sum, since you describe both parties believing they are the only ones benefitting from the transaction. If I buy a $5 sandwich at a deli, it’s not the case that I think they’re suckers for valuing $5 more than the sandwich, and I doubt they think I’m a sucker for the inverse. Clearly, what’s really…
I'm more relying on my experience in trading with Goldman and other banks than I am assuming anything. I also don't see where I said anything about zero sum games.
If I have three shoes, I might correctly place little value on the extra, while a person with only one shoe might correctly place a lot of value on it. My selling the shoe for anything more than $0 is rational, and the other person's buying the shoe for anything less than the price of a full pair of shoes is also rational.