So let me just understand; you wouldn't accept any argument against what someone percieves as capitalism unless they are giving their work away for free? That wouldn't really change the arguments one way or the other, as far as I can see. I don't think Piketty would ever say that capital should not exist, or that we should not buy or sell things, that's beside the point.
Here's something I'm a bit confused about. In what way is a nation a fictitious entity? I mean, I'm from Denmark, and I would certainly say that there is such a thing as Danish culture and history. There are borders, and there is a government. I know that we as anarchist would like there not to be nations, but we can't ignore that they exist as the world stands today. For example, the whole discussion on immigrations, in which FDR members tend to argue against mass immigration, rests on the idea that there are nations with different cultures, and that people from various countries come into other countries and change them. Do you mean that nations don't exist because the borders are man made, and the government is just a word describing a group of people with power, and that the country/nation is nowhere to be found in physical space? Well, in that sense, do families exist? Do companies? Do soccer teams? Or is it because the participation of citizens in a nation is coerced? Then, did slavery exist, or was that just a fictitious entity that it doesn't make sense to talk about?
Besides, the point was not about nations, but that we now seem to be living in a world where it is more profitable to own capital than to work and produce it.