Immigrant outperformance of native-English-speaking students is a complicated topic; the way I choose to look at it is in terms of population competition. India has 1.3B, China has 1.4B, the U.S. has 0.33B. Assuming that the IQ distributions are exactly equal (ehh), for every one 130 IQ American, there are 4 130 IQ Indians, and 4 130 IQ Chinese. If they all compete for one spot at an American university, the Indians and Chinese will have to work much, much harder to win the "top spot from <nation>" than the American will. A look at the questions and scores for entrance exams in undergraduate physics and math for the India Institute of Technology vs. a look at the questions and scores for entrance exams in physics in math for Stanford should confirm this vast gap in curriculum and competition. Any cursory examination of formal education in terms of course complexity, workload, and exam importance of Korea, China, Japan, etc. vs. the U.S. or other western countries should also lay bare the incredible gap in preparation and competition. As I like to explain to those who support a "global meritocracy" for college admissions, the implementation of their plan would result in a majority Asian student body at every single university in the U.S.
The author's work ethic is tremendous- I have never worked anywhere near as hard as he did for that sustained period of time. But the fact of the matter is that a higher-IQ, more-prepared student would not have needed to struggle as hard as he did, and from his description of the foreign students that surpassed him, they didn't. I suspect he would have been happier if he'd accepted his lot much earlier and leaned into a higher-paying, less-hours career and studied physics in his free time.
Another question- did he refuse to quit because he loved physics, or did he refuse to quit because his vision of his life was overly focused on holding the identity of "guy who works on theoretical physics"?
[1] Many people dislike using IQ to measure anything, and its most stringent detractors say that it is a meaningless metric. It is worth pointing out that while IQ is a completely made-up metric, it is a specific measure of memory and abstract reasoning as applied to western-style logic puzzles and patterns. This makes it a useful metric when trying to evaluate one's ability to study and perform western-style math or physics, which are giant collections of western-style logic puzzles and patterns. Many people who believe that IQ does not predict anything have never had the opportunity to spend a lot of time interacting with someone who is so much higher-IQ than they are that it shows in regular interactions. I am regularly shocked at how much more quickly my extremely smart friends can pick up and memorize concepts than I can.