This. There isn't much more to take away from the paper. As an aside, there seems to be some sort of snowball effect that might confound a naive interpretation

This. There isn't much more to take away from the paper. As an aside, there seems to be some sort of snowball effect that might confound a naive interpretation of the role of intelligence. For example, getting a high SAT score (and AP scores) is likelier to lead to Ivy admission. Ivy admission is likely to lead to above average training, as well as more influential social networks. This can lead to interviews with above average firms... etc. You get the picture. Now, intelligence played a role in the high test scores and admission to an elite undergrad, and still plays a role throughout the journey of a successful (whatever the definition) individual. However, there are many feeback loops and amplifying/compounding first and second order effects as well. Quantifying the effect of grit, intelligence, etc seems very difficult.