So I don't want to talk politics here (ha!), but point out the problem of legacy skills in high-tech. The problem with older works is that their skills have become stale. A company coddlingly older workers will be out-competed by startups hiring younger workers.
Consider this graph from Netcraft: Apache has been the dominant web server since the dot-com era. Yet, it's been out-of-date for almost a decade, needing to be replaced by better servers like nginx and NodeJS. 
It's even starker when you look at the most important websites. If Netcraft hadn't reclassified CloudFlare from "nginx" category to "other", then nginx would've surpassed Apache by now on the busiest websites.
Apache should've been wiped from this graph back in 2011 when it became obvious nginx was vastly better. Instead of a quick change, we've only seen the gradual change, because of the legacy effect of workers.
Even today, when I ask corporate IT works, they've all heard of Apache, but most still haven't even heard the name "nginx". BTW, it's pronounced "engine-x" -- I mention that because you've probably not "heard" of it, either :-)
(That last was a side joke -- like most things in high-tech, we read about them earlier, and thus are unfamiliar with a think spoken of even though we may even use it ourselves).
So as for H1B visas and immigration: sure, there are lots of older high-tech workers in America, but they lack the skills desired by employers. The lack of such skills means they search elsewhere, such as young workers from India fresh out of college trained in Go or Rust.
