Not to be too cheeky, but do you have any evidence to support your claim that we would have more monopolies without government intervention?
If you look back through U.S. history, how many monopolies has the government actually broken up? Not many. And I don't think anyone can seriously argue that the threat of antitrust action by the government is what has limited the existence of monopolies.
On the flip side, the government has created or protected thousands of monopolies. As the parent mentioned, virtually every city in the U.S. has granted monopolies to local service providers. On a grander scale, U.S. policy has long perpetuated monopolies for the likes of Standard Oil and U.S. Steel by imposing tariffs on foreign goods and raising barriers to entry through licensing and other regulatory hurdles.
It seems self evident to me that for at least the last 200 years U.S. governments in total have done far more to foster monopolies than they have to dismantle them.