I can only speak for the biological sciences (I am a grad student in bioengineering), but from my perspective this is 100% accurate. My PI got his own lab and

I can only speak for the biological sciences (I am a grad student in bioengineering), but from my perspective this is 100% accurate. My PI got his own lab and his first big grant (R01) in his late 20s. My father did the same at 28. In the lab I am currently in, I have personally witnessed 3 brilliant, qualified, 40 year old post-docs with fellow to faculty transition grants be turned down for assistant professorships. If you go into academic science with the idea that you will end up as tenured professor, then you are naive. As a tenured professor, and even as a new PI, you will not perform much, if any science. You will spend your time writing grants, approaching industry for funding (sponsored research, gifts etc), writing and reviewing papers and editorials, managing grad students, complying with regulations, teaching classes, serving on useless committees etc). There is also stiffer competition for grants every year, making it extremely difficult to stay funded. Our lab does alright because we are heavily industry funded, but individual groups in our lab have suffered. I plan to either go into industry, work for a startup, or start something with some colleagues.