There's a basic disconnect going on here with regards to conflicting narratives of needs, wants, resources, and development of economies. It is indeed absolutely true that the system we live under (global capitalism) has a finite limit on how many people can be sustained in jobs calling for degrees (or advanced certifications, etc.). This limit, however, is an artificial obstacle imposed by prioritizing profit over efficient use. I'd add that we're not even close to approaching that artificial limit anyway. There's nothing etched into the fabric of the universe which magically prevents an employer from, say, hiring 20-30 employees with graduate degrees at around 40k a year instead of a handful of obscenely overcompensated executives drawing seven figures. There's plenty of dogma and mythology presenting ideological resistance, but nothing stopping the actual practice.
But the deeper issue here is that jobs as we currently know them are NOT some self-obvious, natural order inherent to economic activity. Once again, even without challenging the larger system, there's no reason we have to resign ourselves to the job roles and duties we're currently accustomed to. Commercial employers already shuffle job duties on a regular basis when employees are away from work for a long time, when companies split or merge, etc. While there are a relative handful of jobs which -- due to the nature of the work done -- for all intents and purposes must remain specialized, MOST of the things people do for work are NOT structured that way. Can a professor manage to also empty their own trash/clean their own office? Of course they can. Get a few dozen professors to do their own cleaning, and the payroll formerly used to pay a full-time campus custodian could instead be used to train that former custodian into some other more flexible and rewarding line of work. Take your pick of work roles, and this concept can likely be applied.
Basically, making higher education genuinely accessible -- in conjunction with rethinking how work duties are articulated and assigned -- means breaking free of the artificially constrained options built-in to presumptions that "the economy doesn't need more educated people." OK...if the CURRENT arrangement can't support more educated people...then let's change the economy.
This dogged commitment to keeping things artificially difficult...because they're already artificially difficult...is an insult to human intelligence and creativity. Clearly people manage to do new things on a regular basis, yet if we took the It's-Just-Got-To-Be-This-Way meme to its logical extension, we are left with no explanation as to how anything new could or would come into operation. After all, if everyone accepted the idea that we have some magically fixed number of feasible work arrangements drawing upon advanced education, then jobs would function more like heirlooms, passed down like family treasures (which indeed they would be, if it were the case that we couldn't do anything to expand the number and quality of work roles available to people).
Back in reality, of course, humans manage to establish work roles for most people, despite our habit of squeezing out more and more babies and expanding the population. Clearly there is some way (or rather, many ways) to establish new, additional gainful work for people, or we'd have long since become a planet of starving paupers.