The short answer is no, it never has, and it never will. The monopolies of the 19th century (railroads, steel) only existed because those industries were counted as public utilities and given protection from competition by the government. There has never been a case of a natural monopoly (it has been tried). But why is it the case that there has never been a naturally occurring monopoly? The answer is because the moment a company tries to raise prices to absurd levels to take advantage of consumers, entrepreneurs take advantage of the situation, and conduct business offering the same product or service at a lower price, taking all the business away from the company that had a monopoly. If a large company tries putting competitors out of business by putting their prices so low that they are operating at a loss, they would need to continuously do this in order to stop each business that arose after they tried raising prices again. If they continuously operate at a loss like that, then they will run themselves out of business.