>>70035
While I would broadly recommend familiarizing yourself with Austrian theory on general principle, I wouldn't think it entirely necessary to comprehend their comments on monopolies.
A simple argument you might use is to ask your friend to provide a single example of a company establishing and maintaining an abusive monopoly for any length of time without government assistance. Be wary of the popular examples people try to give like the "robber-barons"; ask for actual data to support their claims. What you'll find in pretty much every case is either that they didn't have a majority market share at all and prices were falling (indicating no monopoly and no abuse), or government interference in the form of licensure, industry regulation, government grants of privileges, subsidies, or the like. I put it to you that you will never find compelling data-backed evidence of a single firm managing to maintain abusive control over an industry without government interference being involved. I've been fielding this challenge for years and nobody, not even the most pompous tweed-wearing liberal academics, have ever managed to give a single supported example.