It's not just customer choice. They have all the classical barriers for entry for anyone trying to provide similar product quality. Even if someone manages to b

It's not just customer choice. They have all the classical barriers for entry for anyone trying to provide similar product quality. Even if someone manages to beat them temporarily, Google can compete with prices (of ads typically) so low that they can't make profits but Google can. They bleed out anyone trying to compete. Economies of scale, network externalities and vertical and horizontal integration means that popular internet services are king of the hill type business. Bigger and larger translates to smaller cost per user, cheaper ads and higher quality. There can be only few really big players and they create natural barriers to entry for anyone else. All classical barriers of entry apply to Google, FB, Amazon: * Economies scale production * Limit pricing * High set-up costs * High sunk costs * Advertising * brand loyalty * vertical integration * horizontal integration