Monopolies may happen because of superior technology (or better placement, in short, it's much better for the consumers) or because of politics.
If it's for superior technology, I think the monetary gain is justified. Also, in a world without patents or copyright, everyone is free to reproduce the technology, if they can.
For the market to be manipulated, you would need something that lives outside of market rules, namely politicians who can use violent threats to shape the market to benefit them and their friends.
In both cases, if we get rid of a government and we move law making and law enforcement in the hands of the free market, we end up with a system which is the closest representation of what citizens want.
It may not fair or just according to someone's ideals, but it would be a close reflection of what people wants and it would remove the form of violence which is most commonly perpetrated in the world: state initiated violence.