This is completely false for the free market. A trade in the free market is always a win-win. It is the definition of the free market. If a trade is not win-win, it will not be completed.
Sorry, but this is false.
example:
A trade can also happen, because you
think it's a win for you, but in reality it isn't. (e.g. a retiree that buys a useless insurance)
Or because you lack other options.
Your sentence is wishful thinking, but reality isn't like that.
be a win-win for all parties involved. In order for this to happen there needs to be a sufficient amount of transparency and neither party is able to cheat. Unfortunately this is often not the case.