Being south asian myself—I suspect that the high achieving immigrant-and-immigrant-descended populations gravitate towards technical fields and Ivy leagues for different reasons than American whites do. Coming from hardship and generally being less WEIRD, they psychologically share more in common with the middle class and even blue collar workers than the Ivy League upper class—they see it as a path to success rather than some sort of grand purposeful undertaking. (One of the Asian Professional community I participated in articulated this and other differences in attitude as a reason that Asians often find themselves getting passed over for higher level management positions, as something to be overcome).
Lesswrong tends to appeal to abstract, starry-eyed types. I hate to use the word “privilege”, but there is some hard to quantify things, like degree of time talking about lesswrong-y key words like “free will” or “utilitarianism”, which are going to influence the numbers here. (Not that asians don’t like chatting about philosophy, but they certainly have less time for it and also they tend to focus on somewhat different topics during philosophical discussions and use different words. They’ve got a somewhat separate religious-philosophical tradition)
Another possibility that might make an even bigger difference is that, lacking an organized religion to revolt against, Asians may less often be militant atheists and skeptics. Lesswrong and Overcoming Bias owe part of their heritage to the skeptic blogosphere.
/speculation
Had to make an account to answer this one, since I can give unique insight
I’m an atypical case in that I had the Capgras Delusion (along with Reduplicative Paramnesia) in childhood, rather than as an adult. The delusions started sometime around 6-9 years of age. I hid it from others, partly because I halfway knew it was ridiculous, partly because I didn’t want to let out that I was on to them...and it caused me quite a bit of anxiety, because I felt like I lost my loved ones and slipped into parallel universes every few days. I would try to keep my eyes on my loved ones, because as soon as I looked away and looked back the feeling that something was different would return.
Sometime around 12-14, I realized how implausible it was for any kind of impostor to conduct such large scale conspiracy, and how implausible it was that I was slipping into parallel universe. I told my parents what I was experiencing and admitted it was irrational. I forced myself to ignore the feeling every time it came (though it still bothered me). Eventually around 17 the feeling stopped bothering me altogether, although little twinges still occured from time to time.
I’m currently in what I would consider to be above average mental health, and many years later learned I the name of the delusions that had plagued me as a child. Prior to identifying them as monothematic delusions, I had thought that imposters and parallel universes might simply be a gifted child’s equivalent of monsters under the bed. My parents thought it was from reading/watching too much fiction. I never suspected a neurological disorder until years later.
I’m not sure if I was able to see past the delusion because I’m an atypical case (no known brain injury), because I was a child, because my brain healed via biological mechanism, or because I’m intelligent...but I can tell you that my memory of the event involves me figuring out that the delusion was improbable and consciously working to bring it to an end.
So unless my memories are false (it was a long time ago) or I am engaging in mis-attribution, the answer to your question is that yes, in some cases it would be possible for someone to use rational thinking to overcome this kind of disorder.