Some truth there, for sure. The problem occurs when the monopoly exists in a high-infrastucture industry. If I, for example, owned all the oil refineries in the US, I'd have little worry of someone trying to compete with me.
So my pricing would not be based on keeping customers, as is the case with competitive industries. I could charge pretty much whatever I wanted, as long it wasn't so high that you would be willing to spend millions to build your own refinery.
True, but let's define what a "fair price" is. It is the price at which supply and demand are in balance. So, if the price is low enough to discourage competition (and there is no coercion involved), then what are we complaining about?