And I assert that geographical proximity to peers is a sixth contribution.

The change in topic was when you said "pay huge sums of money" - that's a negative to colleges, and then the question becomes a cost benefit analysis. Previous you were mostly focused on the benefits of college, which is all that I addressed. Hence "change of topic." (Perhaps I should have said "widening of topic"?)

I take it by the absence of a response that you are convinced that arts programs can require more than what a hackerspace-style organization can provide?

> How many people would you guess that would be interested in learning about physics?

"Learning about physics" is uselessly broad. Classical mechanics, electricity&magnetism, thermodynamics, particle physics, astrophysics, and solid state physics are very different aspects of physics. A meetup can't be "learning about physics" but "learning about a specific topic in physics", and likely even "and at the same level of understanding", since an introductory quantum mechanics student likely won't make heads or tails of Cohen-Tannoudji or Sakurai.

(For that matter, my school didn't even have a solid state course for undergraduates, while some other colleges do.)

Why didn't you work out the math yourself? Assuming 6,000 new B.S.s in physics per year out of a US population of 317 million, times 70,000 students in the city => 1.3 students at a senior level.

Obviously at least two are needed for a study group, and some people prefer to work independently, giving a high likelihood that a small city cannot support a decent peer-based physics meetup group. FWIW, our study group had about 5 physics majors, out of 15 in the graduating class.

To put it another way, I grew up in Miami. The Miami metropolitan area has a density of 890 people/sq. mi. That's 1 physics student for each 60 square miles. For two nearby students to meet requires a minimum average of 5 miles of travel. More likely there's 30+ minutes of travel for each hackspace-style meeting with 5 people. While on campus, when most people live on or very near to campus, the commute time is a lot smaller. Thus, moving to be close to peers can increase the amount of time available for studying and practice.

You then added a new thesis to the mix, which is that "colleges are the gatekeeper to knowledge."

They most certainly are not. Colleges are the gatekeeper to certification in some fields (as your #5 points out; and as a real-world example, a Master of Library and Information Science is required for most professional librarian positions).

But "gatekeeper to knowledge"? Nonsense! How did you get that idea? What does it even mean? What knowledge is prohibited or withheld from those without a college education? Are you sure you aren't just using that term as a scare tactic?

So, ways to disrupt the expensive college education system of the US:

1) free or highly subsidized college education for anyone who wants it, in any field whatsoever.

2) minimize the importance of a (semi) classical liberal arts education and promote trade, craft, and technical colleges as the better route for certification-based skills training.

3) subsidize adult continuing education for those who have done #2 and still want a general liberal arts education. (A town of 70,000 people can easily have a few people interested in a common sophomore level course every other year.)

4) set up something like the Open University, that is, a state school/non-profit which has distance learning for those who can't attend a physical college for all classes, and with research/lab space for those courses which need it.

Is that disruptive enough for you?

Like I said, I see education as a general social good, and not a simple cost/benefit analysis for a single person's own career.