Demand has also dropped since the quality of post-secondary students has regressed to the mean of society. Schools used to be more selective, and you'd only get in if you were in the upper percentiles of society in terms of aptitude, ability, and work ethic. In the 60s, only 10% of people had college degrees. Now almost any high school graduate can find a university program.
Unfortunately the selective outcome was marketed as achievable to anyone who goes to university, leading to swathes of people forking over money expecting the best result.