I don't understand your argument. I never said any value is fixed. Of course a person's value changes from role to role and from company to company. Part of doing your research is understanding the pain points for the company and the value you bring by fixing those pain points.
If you disagree with "a professional knows their value," what are you arguing? That "a professional doesn't know their value?"
If you disagree with "a professional knows their value," what are you arguing? That "a professional doesn't know their value?"