The opposite of "monopoly" is not "disruption" but instead "competition." Disruption moves a market equilibrium, usually due to a fundamental change in technology. But even a market in a steady-state equilibrium are subject to market forces so long as they are sufficiently competitive.

E.g. Amazon is disrupting retail. But even before Amazon existed, retail was highly competitive, with market forces driving down prices. (Indeed, there is a good argument that Amazon is decreasing competition even as it disrupts the market.)