[gwern]

You're not adjusting for risk here. In tech, the norm is for industries to die within decades - how many tech giants are still around from the '80s? IBM, Microsoft, Apple (after a near-death experience), Oracle and... that's about all I can think of.

On top of the mortality rate, unlike a publisher or a journal, a dead tech giant leaves behind nothing that will still be valuable decades later: the technology is long-since obsolete, the brand irrelevant, and what intellectual property do they have? Their patents expire within 20 years while the publishers and journals' copyright on anything written since the 1930s will last what might as well be forever.