One failure mode of unchecked and unregulated capitalism is the establishment of monopolies that can starve oxygen from the rest of the ecosystem.

In order to have maximally efficient and broadly beneficial capitalism, you need strong anti-trust mechanisms to reoxygenate the environment for new competition. Regular enforcement also means that labor and investment capital reap the most rewards instead of calcified, legacy incumbents.

Companies need to be constantly fighting to survive. If they're sitting comfortable and growing without controls, something went wrong and the rest of the fitness landscape is being distorted by an invasive species.

Antitrust Regulation is incredibly pro-market and pro-competition.