Edit: Changed title to be more accurate.
Also here is the summary from Wikipedia on what Post-scarcity means:
Post-scarcity is a theoretical economic situation in which most goods can be produced in great abundance with minimal human labor needed, so that they become available to all very cheaply or even freely. Post-scarcity does not mean that scarcity has been eliminated for all goods and services but that all people can easily have their basic survival needs met along with some significant proportion of their desires for goods and services. Writers on the topic often emphasize that some commodities will remain scarce in a post-scarcity society.
Capitalism is a Mode of Production by which the Means of Production are bought, sold, and traded among individuals. This results in Capitalists, ie owners of Capital, and Workers, those who Capitalists employ to create Value using said Means of Production.
And what’s the problem with owning, buying and selling things? We’ve been doing that for millennia. Obviously, unregulated American style capitalism is very broken, but there are better ways to do business. It’s just that those ways are not that appealing to the greedy.
Markets aren’t Capitalism, Capitalism has only been around for a few hundred years.