If player1 can make the same widget with less resources than player2, its not zero-sum. That does often entail that player1 has some advantage, which could be any number of things. Is that OK?
It happens because the less wealthy player has a lot more to loose then gain in an unequal economy. That is even if a trade outcome is favorable to the less wealthy player, it is unlikely that the outcome is significant enough to change the balance. However it is much more likely if an outcome is unfavorable that it will significantly hinder any future opportunities for the poorer player.
On the other hand, a loss for the wealthier player is unlikely to significantly effect future outcomes for them. The only likely way for a wealthy player to have a significant loss if they land a devastatingly bad deal with another equally or more wealthy player. The chances of that happening at random is pretty low overall, and gets lower the wealthier you are.
First. The greatest predictor of individual wealth is their parents’ wealth. This undermines the whole notion of the free market (or at least in its current state) giving rise to a meritocracy.
Second. Statistically, in a completely free and fair economy where all trade is zero-sum and every player will either loose or gain from a trade is up to pure chance, the money in the economy will accumulate to fewer and fewer hands as the number of trades increase. This is a pure statistical phenomena, meaning that as long as some players have more wealth then others, those players have an upper hand in any future trades for that reason only.
The meritocracy of capitalism is a pretty well debunked theory at this point.