She apparently went from 6th grade math to graduate quantum mechanics in a year and a half. This is highly atypical and is surely not an example of a "not smart" person overcoming and managing to learn some physics.
Furthermore, if your goal isn't to do research work but rather to be able to follow along an average research article using the basic framework of QFT, you can also cut out much of the lab work. Susan is clearly considerably above average in intelligence and a quick study, and I'm impressed by her perseverence, but I don't think this is at all beyond what any good theoretical physicist could have done. It's just that they went a different path, going through the university system, a path with its own advantages, but brevity is not among them.
EDIT: she was homeschooled, which explains it...more info https://www.susanjfowler.com/blog/2016/8/15/20-unconventiona...
Obv. profoundly smart
The question is, is her almost overnight success reproducible by other smart people. Let's say you know calculus and linear algebra, QM is doable, I suppose. But still...mind blown. Even Ed Witten with a physicist for a dad still took 4-5 years to learn the stuff.
What may be MORE interesting to see, not just for HN folks but in general, would be a parameterized set of possible/reachable (as well as 'stretch') goals, for folks interested in learning more about math/physics/cs at various bands of natural/innate ability. While these bands may not be set in stone and raw effort may help level up someone up one tier above their 'home' range, it is for instance frankly impossible for at least 99% of folks to ever become competent at QFT - and likely, 95-99% cannot even grok it in part.