[WarmWash]

I think you may be conflating "dominant player(s)" with "monopoly". The US has close to zero monopolies if you disregard natural/patent/IP monopolies.

Its not illegal to have a product that consumers overwhelming prefer over the competitors. Google was ruled a monopoly because it was paying other services to default to Google. But it was ultimately foolish for Google because people given the choice still overwhelmingly picked Google.