In fact, Thiel seems to be running into the old diamonds-and-water paradox – water is essential, but costs nothing, whereas diamonds are virtually useless, but extremely expensive – albeit in a sophisticated and subtle way. The paradox exists because, in a market economy, the value of water is set not by the total usefulness of water (infinite) or by the average usefulness of water (very large), but by the marginal value of the last drop of water consumed (very low).