Conspicuous consumption — buying what others can’t afford — is a disequilibriating force. Prices get raised and supply is limited. The goods that are conspicuously consumed are positional goods.
A similar phenomenon occurs in the stock market. AAPL currently seems to fit the mold. Fashion changes. I don’t much believe in predictions, but I predict that “bite of Apple” will have a new connotation in the foreseeable future.
Perhaps the best possible explanation of “positional good”.