Take natural gas. Let's say there's a first company that has laid pipes to all the houses in town. Currently, they're a monopoly, just because they were there first. No government involved. They may be pretty profitable, too, in the absence of competition. And they're remain a monopoly until some other company lays pipes to at least some of the houses in town. But no company will do so, because they know that if they do, the first company (who has years of profits to build up their financial reserves) will lower prices to the point that neither company makes money. The new company will go out of business, and the established company can then raise rates back to what they were.
It takes government intervention to stop this dynamic. And, with electricity and gas, it usually takes one of two forms - either a public service commission that prevents the monopoly from making too much money, or a requirement to allow competitors to use the existing pipes/wires. But neither of those created the monopoly. They just responded to the fact that natural monopolies are what naturally happen in things like electricity and gas.
Your claim was broader than natural monopolies. You said "All of that requires government". How does one company buying out their competitors require government (beyond having money and a legal system)? (And if the claim is "money and a legal system require having government", that's true, but it's true for all companies in general, not just monopolies, so that's pretty much not the topic under discussion.) How does one company using leverage to monopolize a market require government?
For a concrete example, when Microsoft was using Windows as leverage to try to monopolize the browser market, how did that take government? It took government (an antitrust court case) to stop them.