The idea that a US citizen could rack up tremendous debt on a 4 year STEM degree only to be passed over in favor of a cheaper H1B "indentured servant" that received a degree from a low cost diploma mill is vile indeed.
What sticks in my craw even more is that, to legitimise the process of issuing more visas, companies and governments have to continually say "there aren't enough STEM and IT grads! Do STEM and IT everyone!" knowing full well that there wont be jobs for these kids at the end of it.
My Niece is in a field that's chronically low on qualified Engineers - she designs and installs automation in factories. So many facets including mechanical, electrical, industrial, chemical, process, thermo, etc. You have to be an all-rounder to get the job. So they work her flat out every minute she can spare (lives in hotels in remote cities for weeks during installs).
Other niece does lithium-battery development for startups in Silicon Valley. They keep going under, but no problem another one starts up the next week. Got all the work she can handle.
Wife's niece does biomedical research, never been a day without work. Canada, East Coast US (Yale actually), then a regular job with Govt.
Anyway, of the 13 siblings and their cousins, exactly 1 has ever had a day of trouble with employment. So all the talk about 'over-supply' might be exaggerated.
Someone will be along with an equivalent tale about how they and everyone they know looked for a STEM job for years and gave up. That's why anecdata isn't actually a thing.
There're other effects, things labeled 'white privilege' or 'middle class ethics' I imagine. So no, not a recipe for escaping poverty or anything. I was the son of a dirt farmer in Iowa (like my sisters and brothers), but worked in Silicon Valley when young so my boys didn't have the disadvantages I did.
The data is all out there with regards to the level of unemployment and underemployment amongst STEM and IT grads, the number of people who have to seek employment in alternative industries, and the level of stagnation of wages in the industry. It's not at a level which indicates systemic failures, but it's significant enough to raise questions.
This doesn't condone what the body shops do, but I don't see a problem H1-Bs being used to address regional shortages in the labor market. But the program absolutely needs to have a regional component given that the scarcity of talent really is regional. We should not be issuing H1-B visas to work in cities where US workers can't find jobs. And H1-B priority should be given to companies that employ the lowest percentage of H1-Bs. With a few other provisions to ensure similar pay, this would destroy the companies that rely almost solely on H1-Bs without hurting tech companies that legitimately need H1-Bs to address the difficulty in finding talent.
If it wasn't for school, I would never had known where to go after I learned the basics, that is, Data Structures and Algorithms come next, then applied knowledge. Because of the school that I went to, I have a high level knowledge of programming language design and paradigms, OS and systems programming, compilers, encryption, security, and privacy. I also, because I double majored, know more than I want about signals processing and really the only thing in your list that I didn't get to touch on was ML/AI which was unfortunate.
But to your point, College has always been about self-education no matter the subject. The general guidance has always been that for every hour spent in class, you should be spend 2-3 out of class studying.