I was wondering what where the source for studies about income increase over the course of the career, then I saw your post and realized multipliers were extremely warped by the minimum wages laws. If one starts to work before reaching full initial education level & in a place where there is next to no minimum wage, it's possible to start very low and easily mechanically reach a larger multiplier over the course of a career. With a minimum yearly unqualified wage of € 19,000 in France or € 26,400 in Luxembourg, getting x10 over the course of career means reaching far above the top 1% salary bracket (and I'd say not all people in this category started with a minimum wage job).
Interestingly, and pertaining to the topic at hand, when adjusted for inflation, SKR was better paid at Interplay than in the RPG industry, even with 20+ years of professional experience. Which isn't surprising.