The rule of thumb is that the company expects to generate profits at least one order of magnitude larger than your salary. Hence I would say the 80K hacker should be able to do work worth about 1 M a year to the company.
This gets back to PG's second assumption: "Assume a hacker can in turn be significantly more productive working for themselves."
Most hackers are not more productive working for themselves for a multitude of reasons, some of which have been discussed (i.e. lack of marketing focus) but I think that most hackers who work for someone else hone very specific skills that are suited to the task at hand, which build value for the companies they are working for, but those skills arent necessarily valued in the marketplace.
This gets back to PG's second assumption: "Assume a hacker can in turn be significantly more productive working for themselves."
Most hackers are not more productive working for themselves for a multitude of reasons, some of which have been discussed (i.e. lack of marketing focus) but I think that most hackers who work for someone else hone very specific skills that are suited to the task at hand, which build value for the companies they are working for, but those skills arent necessarily valued in the marketplace.