My dad explained it to me like this when I was a kid. I ignored it for a long time, but it definitely stuck in the back of my head. I asked him if we wanted to get a promotion or be a manager but he said he thought his role as a documents library was fine.

"Do you know the Peter Principle? It's the idea that you get promoted when you do good work, but at some point, you'll be promoted to a level you're not competent to do, and get stuck there, or fired." He then expanded: "In this case, I perceive that the additional responsibilities and stress associated with a higher level position or management would make me unhappy, and I don't truly need the extra money."

For nearly my entire career I have pursued advancement with the utmost drive. Originally that was going to be grad school->postdoc->professor at major research university->make amazing discovery but at some point I realized that I was only ever going to be a professor as a minor reesarch university (and spend hundred+ hours a week treading water) and switched to the postdoc->software engineer->tech lead path. It wasn't until I did the Tech Lead role, got promoted to L6 and started to think about being a manager or getting to L7 (or getting Exceeds at L6) that I started to realize the truth of what my dad was saying. I've reached a level I'm perfecetly comfortable at, and could stay here until retirement. I was mainly chasing the advancement for ego and money reasons.