In an unregulated market competitors will disrupt big business.

In a regulated market big business will bribe the government and keep its monopoly, increasing inequality between the top 0.01% and the plebs.

The arc of the U.S. economy over the last 80 years contradicts your position. There has been reduced regulation since the Reagan administration, and also reduced competition. A few blips when internet companies "disrupted" an existing industry, but those industries fairly quickly consolidated on a small group of players.

You're describing regulatory capture, which is true in unregulated capitalism. When I say "unregulated capitalism", I'm not talking about business regulation---I'm talking about regulating capital itself. In a healthy, regulated capitalist system, the political influence of individual companies is diluted and there is greater competition. Business regulation is always needed to ensure things like public safety, contract enforcement, and fair competition. But when disproportionately large players politically capture the regulatory machinery, they tilt the regulatory playing field towards themselves. This is a symptom, it is not the disease.