> If being in the U.S. didn’t offer advantages they wouldn’t be here to begin with.
For companies hiring H1Bs it's about being closer to clients and colleagues and just being managerially far easier than opening an offshore office, but the benefit isn't infinite and once companies have the chops for opening new offices they'll turn down the H1B hiring.
The issue for the US is that, are you're saying, "having faith in your own country" only works if you have the process for developing unnaturally skillfull talent, which is just not going to happen once the smart people stop moving to the US as countries have uniformly distributed talent potential.
You seem to have interpreted "have faith in your own country" as "have faith in the people who grew up here" whereas I interpreted it is as more like "have faith that the parts of the country's institutions and culture responsible for its excellent economic performance will continue to prove difficult for other countries to replicate".