If everyone in society had a college degree, they wouldn't increase salary by $80k. They already don't for most people and if you increase the supply...
I don't see how your interpretation is based in anything other than wishful thinking.
>> If everyone in society had a college degree, they wouldn't increase salary by $80k.
Free education doesn't mean that everyone has a college degree. It means that everyone who chooses to study for a college degree has the opportunity to obtain one.
Most colleges and universities in the USA were non-profit, until the 1970's. Everyone didn't have a college degree back then.
Finally, as an aside- it's a bit problematic to measure the value of a college degree just by monetary gains alone. Job satisfaction is at least as important and probably more.
I don't see how your interpretation is based in anything other than wishful thinking.