Implicit is the presumption that the smartest people optimize for wealth, or that the smartest people are good at optimizing for wealth. Outside of Wall Street, "smart" people - academics, doctors, lawyers, engineers, etc. - are just as likely to make bad personal finance decisions and/or to stay in labor (rather than management) positions for most of their careers (leave aside the dual-track IC/management ladder at a relatively small handful of companies). People don't bother to max out their earning potential because, after you earn enough to meet your needs, it quite frankly doesn't matter anymore compared to other means of personal fulfillment.
This is besides the point that the ranks of upper management are typically filled with people who are socially/politically smart, and not necessarily STEM-style smart; the cognitive ability of whom may or may not be adequately captured by this study.
This is besides the point that the ranks of upper management are typically filled with people who are socially/politically smart, and not necessarily STEM-style smart; the cognitive ability of whom may or may not be adequately captured by this study.