An "endowed chair" is the best type of full professorship, but it's an exception rather than the norm. There are elite institutions where most full professorships are endowed chairs, there are very wealthy institutions where that happens for lower titles, but in general most professorships are not as such.
Furthermore, it's not something that's available right away (exceptions do happen for exceptional people, but they're exceptions).
For a random example of a successful professor, look at the carreer ot Terrence Tao (https://www.math.ucla.edu/~tao/preprints/cv.html), James and Carol Collins chair in mathematics at UCLA. He got his PhD in 1996, got full professorship at 2000, and was a non-tenured non-chaired Assistant Professor for the four years in between.
Seriously, just look up a random professor from your local community college (not something like Stanford) and take a look at their CV - how many years it took for them until the full professor position.
Furthermore, it's not something that's available right away (exceptions do happen for exceptional people, but they're exceptions).
For a random example of a successful professor, look at the carreer ot Terrence Tao (https://www.math.ucla.edu/~tao/preprints/cv.html), James and Carol Collins chair in mathematics at UCLA. He got his PhD in 1996, got full professorship at 2000, and was a non-tenured non-chaired Assistant Professor for the four years in between.
Seriously, just look up a random professor from your local community college (not something like Stanford) and take a look at their CV - how many years it took for them until the full professor position.