Wallstreet Bets

It's reductive but profit in that sense isn't required for commerce and trade. As in, it is possible (technically) for commerce to exist and every trade be fair, there isn't really a fundamental law of the universe that requires commerce to be for profit.

The point they were likely making is that, in typical capitalist systems, the capital owners fundamentally make their money by finding arbitrage in the total cost to produce and the sale price.

Looking at it as an abstraction of any individual items it's, in order for the capitalist to make money from capital they must extract the value from the trade and keep it, e.g. the item costs $10 and is sold for $11 and the capitalist keeps $1. If the item really cost $10 to make then the extra dollar is just overcharging.

Whether or not you think that the overcharging is fair is where the arguments happen. The capitalists argue that their ownership offers an intrinsic value (the risk), opponents argue that it doesn't. And so the capitalist argues that the item cost $11 to make and that their stake is part of the cost.

It is true that in a profit bearing scenario, someone has to be the loser and it is inherently zero sum, you cannot make a profit without someone along the line not getting the value they are entitled to.

It may feel like simple transactions are fair, but what typically happens is that fractions of a percent are scraped off throughout an entire chain of logistics, whether it's slave labor over seas, or just more blatant things like creating 'value' by introducing artificial scarcity, the abstracted end result is someone getting more value than they create which means someone else must get less value than they create.

I'd like to add that communism doesn't actually solve this problem, because an inherently fair trade doesn't always mean that both parties are equitable. Some people are able to produce more than others. Systems like communism, typically aim to make things equitable for everyone, not fair. I think it's an important distinction because a completely 'fair' system would be a true meritocracy that leaves people with less capabilities behind.