The problem is often technology becomes a barrier to entry especially when it requires scale to operate. AI is the extreme example of this kind of technology - needs large compute, and large amounts of data, and requires a actor with enough capital to create it. In effect a lot of modern technology has helped create monopolies.
The barriers to entry definitely exist, but is it the technology itself that creates them, or is it the intellectual property laws we've adopted? Capital is a barrier but it's far from an insurmountable one -- there's plenty of capital floating around in the world. As a thought experiment imagine what the tech industry might look like if the US introduced some form of compulsory licensing for software (for patents? for copyrighted source code?) like what exists for music.
Natural monopolies certainly exist in sectors of the economy like public utilities, but I don't think they are so strong in tech.
For me monopolies, even natural ones, are maintained due to power structures in society. If you see most natural monopolies that are privately owned there's usually a political system that allows that to occur and a well connected powerful actor. AI has the ability to break the one power structure keeping the middle class intact - that being they still technically need people to "think on the ground" to provide the things they want. i.e. output is still a function of labor. AI breaks the need for "labor" to be a required input into the production line long term - i.e. it will no longer be a large economic factor of production.
My personal view: AI makes most of the world's population in the long run surplus to requirements for people who own capital, societal power and the planet's scarce resources. That's a form of monopoly.
