Capitalism allows people to own business and property, and gives them the LEGAL ENTITLEMENT to the profits from those businesses and properties. Those people are owners. They own chunks of the earth, farms, factories, buildings, houses, freshwater sources, EVERYTHING that the rest of us require to survive. Reddit thinks the distribution of property is unfair and it causes a lot of suffering when people aren't able to meet their needs because they started life with such a small share of the earth's resources, that the only available option is to enter into what they describe as the unbalanced contract called “employment” where at the end of the day they are working to make the owners richer at a faster rate than they are making themselves richer.
Reddit HATES the idea of billionaires. But billionaires are simply owners who control a very large portion of the earth's resources. Reddit thinks there is something very wrong with the idea of having not just the resources needed to have a very good life but to have resources far, far, beyond than what can ever be consumed by one person, one family, or even a small nation.