You just aren’t paying attention to what I’m saying. It can’t be a monopoly when you have competition as well as the ability for anyone to enter the market.
Let's see how this works. I'll be given a monopoly to deliver newspapers to 500,000 houses in the city, and the people who live in those houses must pay a rate that covers my expense of printing and delivering the papers. I can even roll any added costs for additional space in under that same rate.
Now I go to businesses to sell advertising in those papers. What is my overhead to including their ads? Just about zero, so if I sell $20,000 in ads for Sunday, I'll make right abut $20,000.
How about the competition? What is their overhead to print and hand deliver the same amount of advertising to those 500,000 houses? Its certainly more than $0.04 per house, which means they'll lose money.
Are other parties prohibited from entering the market by law? No. Are they prohibited from entering by simple mathmatics? Yes.
If that doesn't make sense to you, imagine I'm being given Snickers bars for free and selling them for 50 cents each. Are you free to go buy some Snickers bars at 50 cents each and compete with me?