Monopolies are the most profitable structures of the market but they also create a loss of Social Welfare, that´s why the regulators always need to be alert to this situations...
Of course Warren Buffett see this profitable companies and decide to invest in them, but the question is, where are the regulators and why are the regulators of the US not preventing monopolies from existing?
Because, if Warren Buffett's Billions come from investing in this situations, then it means there are a lot of companies being a monopoly without proper regulation to protect the society.
The regulators are a major part of the problem...they are all in cahoots, hence the term 'cronies'.