> If I sell my house for more than I paid for it, it's zero sum since someone simply provided me that money. I think the point the author was trying to make is

> If I sell my house for more than I paid for it, it's zero sum since someone simply provided me that money. I think the point the author was trying to make is that you can participate in the housing market by building and selling houses, with the former being “positive sum” (since the land and building materials have a cumulative value less than that of a finished dwelling). The positive sum stuff seemed to be describing markets, not individual transactions