[jltsiren]

And my point was that academics whose primary job is doing research in someone else's project are even rarer than tenured professors in research universities.

A postdoc is primarily a career advancement position rather than something where you are expected to contribute full time. Such positions are also pretty rare. There are something like 70k postdocs in the US, vs. almost 190k tenured or tenure-track full-time faculty in research universities.