You might be interested in a RAND study (a historically very pro-immigration institute) that considers this subject. It concludes that the reason US citizens and people who are free to choose their profession in the US avoid these degrees because they can earn more with more stable career paths elsewhere.
In other words, the aversion to STEM among elite US students is rational.
https://www.rand.org/content/dam/rand/pubs/issue_papers/2005...