The Economics of Toil

As a baseline, everyone has a certain amount of toil which must be allocated to or from them in order for them to survive.

To support a leisure class (not just the rich, but people like CEOs, professors, and marketers) some people must toil much harder than they need to support only themselves in order to allow for this class to exist. This is why the human race has historically relied on slavery, and we still use economic conscription (sometimes brutal) when we're not using outright labor camps to produce goods and services. Without this de facto slavery, humanity could not really advance.

This will always be true short of us automating everything and/or achieving a post-scarcity economy (freeing us from toil altogether)

Under most forms of socialism (excepting models like mutualism and collectivism that allow for wealth accumulation) everyone must toil to support both themselves and the overhead of the community, meaning everyone is working beyond what they need in order to have baseline survival. Everyone is indentured, even in its ideal and theoretical form, never mind in practice. It cannot support a leisure class in its pure form. Maybe that's why the Khmer Rouge set about murdering academics.

Under capitalism, the toil is not evenly distributed, so some people toil so others do not. This creates class disparity and "unfairness" (life isn't fair) but allows for a thriving leisure class and the human advancement that comes with it.

Post-scarcity would make all of this obsolete, but we're not nearly there yet, if we ever will be. I think that would probably be a type 1 society on the Kardashev scale, and if so we're probably a century or two away from that, assuming we survive.