Oxfam don't have the monopoly on truth

Oxfam’s annual wealth inequality press release features a startling statistic. And no, it isn’t that the 85 richest people in the world could fit on a single double-decker bus. They claim that 2/3 of the world’s 2,043 billionaires got their wealth through cronyism, inheritance, and monopoly.
I won’t dispute the numbers for cronyism and inheritance. But, I was curious to see what they define as monopoly. After rummaging through their briefing paper I found a citation to a report called ‘Extreme Wealth is Not Merited’.
In the paper, they try to identify whether wealth is the result of inheritance, cronyism, technology, globalisation, or monopoly. They reckon that nearly 20% of billionaires owe their fortunes to monopoly. That seems high. Let’s see how they worked that out.
They make some bold claims. First, as part of their measurement they identify any IT firm benefitting from substantial network effects as monopolistic. As I argued before, this naïve ‘winner take all’ theory of network effects doesn’t fit the data. They assume that there is intense competition at first, but as soon as one major players emerges network effects create massive barriers to entry. The author argues that even if the initial phase of competition was furious, the rewards to the winner are unfair. Strangely, the author doesn’t even argue that this process is inefficient or harms consumers. Rather, they argue that the network externality benefits would exist even if another firm won out.
It’s a rather strange argument. And it should be seen in full:

“However, the externality exists independently. It is not a product of the business strategy, but is inherent to the nature of the product. Information technology billionaires thus capture and benefit from network externalities, but they do not create them. So the source of the extreme wealth, the externality, is not something that the billionaire contributes to society. Talent, effort, and risk-taking are certainly necessary to capture and benefit from the externality. But the wealth concentration that the externality creates is not proportional to, and indeed is largely independent from, that effort, talent, and risk-taking. It is the externality (e.g., the fact that everyone wants to use the same social networking website, whichever it is) that creates the extreme wealth, while the business strategy merely determines who gets it (e.g., a better-quality site is more likely to capture the externality, everything else equal). Network externalities create winner-takes-all markets where, by necessity of the nature of the product, one individual can become extremely rich while others, perhaps slightly less talented or simply less lucky, get nothing. Thanks in large part to network externalities, the founders of some leading information technology companies have accumulated wealth thousand or ten thousand times as high as that of their unsuccessful yet equally talented—or only marginally less talented—competitors (i.e., billions or tens of billions of dollars compared with millions, which is what most talented computer programmers can expect to earn in their lifetime)."

They also worry about vendor lock-in (bundling). Where firms with monopoly extend their dominant position in one market into another by bundling goods together. This would be illegal under competition law in the UK and US. Oxfam’s assumption is that antitrust enforcement is too weak. Perhaps, it is but extraordinary claims require extraordinary evidence.
However, the next step is crazy. Even if you suspect that there might be some monopoly power in IT (Facebook, Google, Microsoft), it’s a bold claim that all wealth generated in IT is the result of monopoly yet that’s exactly what they do.
To quote their report. Any billionaire whose “wealth [was] mainly acquired in the information technology industry (presumption of network externality, vendor lock-in, and public good market failures)” is classified as owing their wealth to monopoly.
They also classify billionaires whose “wealth [was] mainly acquired in the finance, health care, and legal industries or as CEO of a company that one has neither founded nor inherited (high presumption of the asymmetries of information market failure)” as owing their wealth to monopoly.
I’ll leave the reader to decide whether Oxfam’s 2/3 claim is fair.